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It depends on you riding style, the roads you ride, and bike tune / spec. But for me, I would take the better midrange all day over the better top end.

Your options, in my order of preference:

More midrange power
Fit and Quality both 2nd =
Price
lighter weight
Peak power
 

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Question - if you had 2 different systems and one made more power at 6k but less at 7500 vs the other system that made more peak power at 7500 but less at 6k, what would you prefer? lets say 3-5hp difference at each rpm point mentioned above?

also, what is the order of importance

peak power
more midrange power
lighter weight
fit
quality
price

how would you prioritize this list?

i have been doing a bunch of testing on my 900 and just curious what all of you think is important?

Thanks for your comments
What you really need an answer to is "What is your dream ride?" Then build your bike to suit it.

This is a totally loaded question. "Best" or "preferred" means different things for different people. On a track with long straights I might sacrifice a little cornering out power (mid range) to carry more speed in the straights (top power) and make up time against bigger bikes. Alternatively, carving a canyon road where there is never really enough space or bravado to use all the power on hand, I would stick with building more mid range power that you can easily access.

My dream ride is the latter, and I've built my bike to suit it. I'm a devotee of Colin Chapman's "add lightness" philosophy - if it weighs less then you need less power to do the same thing PLUS handling improves. I balance cost/quality similarly, which is why just about everything on my bike is second hand, but it's fitted with front/rear Ohlins, Termi carbon exhaust, Marchesini forged wheels, radial masters, hi-comp pistons and FCR's.
 

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Do not forget there are some talented exhaust builders who will Make you what you want (if you know what that is). In the north east I use someone who does very nice work and we have worked together on a few projects from de-cat-ing bikes to full systems. Most of his 2-1 systems sell for about $1500 but are made to your bike so they fit perfectly with no wasted space. You may have someone in your area that can do the same.

Expecting an exhaust to make more Hp is kind of like expecting a supermodel to be good in the sack, we assume because someone somewhere sometime saw gains that it was all the exhaust and we all want some of that. Given we are talking about 2-valvers we typically want aesthetics more than performance and will happily take whatever gains come along with the pipe. If we are talking about a race bike where Hp does matter more then you need to involve a Dyno,a pipe builder and start with a flow bench for your heads.

I have a couple Doug cook exhaust systems and I can tell you one did help HP the other probably hurt it, it was all my fault that the second one hurt power as it was my request that it meet certain parameters that probably hurt flow but help aesthetics (for me). I wanted a system that was an undertail with megaphones and ran the pipe inboard (not outside) the swingarm. Doug delivered on all of these points and I do not care if I have lost a few Hp as I love the system.

This is my point some (many) will want a termi label and nothing else will do. Others want a spaghetti system without knowing that they were often designed for higher rpm use ( I assume this is where EIGHTfortyEIGHT was going) and often will not show gains where most stock 2-valve motors live. This is as much a matter of building the bike you love with whatever parts works for you. A friend calls it a high garage contemplation factor, you need to fall in love with the bike even when you are NOT riding it much like that supermodel.
 

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"...like expecting a supermodel to be good in the sack,.."

And if she's not who cares, I'd do her over a fugly that is a performer and I'd bust a nut just lookin' at her LOL.
 

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Thanks for the feedback so far guys.

For the last year I have tested most types of systems and had custom ones built for testing as well. I personally like the midrange. A bike with 8 more HP at 6k always feels better on the street than a system with 2 more HP at top. I personally have a 749r for the track, and think that most use their 900ss like I do for a great street bike and canyon runner. However some people cant get over that peak number thing though. The fun part has been testing so many different systems all on the same bike and seeing what different character they have.

I have to compile all the Dyno plots on one graph to show ya what we have come up with. I have access to a brand new Dynojet 250ix with WinPep8 that I can use anytime I want, so I just keep testing :grin2: It has taken a long time, but I finally have what I wanted over my Spaghetti race system that disappointed me with its street performance. Maybe I was hoping for the holy grail of better by alot everywhere, but that really is not completely possible it seems. The current system I am testing is a 2:1 with a crossover that can be run open or closed. Open it favors the top end, closed it favors the Midrange. I'm thinking I am going to just leave it closed.

More to come as I get closer to figuring all this out.
 

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The current system I am testing is a 2:1 with a crossover that can be run open or closed. Open it favors the top end, closed it favors the Midrange. I'm thinking I am going to just leave it closed.
This seems the perfect candidate for an Ignitech output and a servo actuated gate.
 

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Here are some Dyno plots of the new 3 step 2:1 with a Termi can vs some Systems you are familiar with.

First is the new 2:1 vs a Termi race system



Next plot is the final 2:1 vs a SilMoto


We also built a custom 3 step Spaghetti System like a Staintune. This is the 2:1 vs the Custom Spaghetti


Comments?

A lot of testing on various length systems, now some work on Diameters soon with another test system.
 

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Thanks for posting these up EIGHTfortyEIGHT, do you have more data to add?
It's interesting to see that dip in the curves of the TERMI system at 5.5 - 6.0k
My mind is telling me I like the SilMoto chart, but that's probably because I have one sitting in storage waiting to be installed.
I'd be interested to see pictures of how you have the pipes configured, and to know ID of the systems you are testing.
As always thanks for sharing the data.
 

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It would also be interesting to see AFR to determine if it would benefit from EFI fuel mapping or carb tuning.

Horizontal and vertical would be great - a bit of an obsession with me wrt EFI.

My 81 year old mate always says, I will give you the air, you give me the fuel to match.
It is a bit more sophisticated than that, but this is a basic principle.
 

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I've never worked out why such a well-made system from a desirable manufacturer appears to have the final pipe joint around the wrong way. To me, the downstream pipe should be external to the upstream pipe. :confused:
 

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45mm sill exhaUST

Is there someone here that can tell me if the exhaust will accept Termio or D&D exhaust that fit the stock exhaust?
I have Termis and D&D ...I am interested in the pipes but want to know if they fit what I have or if I need specific exhaust cans for the Sill
 

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Greetings, I've got a full 50mm Akrapovic spaghetti titanium system on my 98 FE , love it ! Put it on when I purchased the bike new in 98 , and personally haven't ever seen another one like it, no fitment problems.
At that time,I think Termi was the only other one doing the full spaghetti and those were limited as I remember. Mine has a real nice tone/sound and not as loud (or too loud) as a lot of the other cans.

It also works excellent with the big bore 944 kit /Kehin 39's and extra internal engine work... goodies like marchesini mags/ohlins/ etc don't hurt either , a sweet package I've enjoyed for 20 years and 8400 miles.. unfortunately,
in my old "retirement" age I just can't ride very far without a lot of aches and pains ,so am going to let her go to a new home, and guess put it on the market (can't advertise here yet as I don't have enough posts I think)
And I just pulled the trigger on a new Multi this month , that should ease my "pain" and will give me something to look forward to as the weather improves , and snow melts <sigh>
but I did roll the new red multi out of the garage and into some snow for a few pics ...it did look very "Christmasy "
cheers
 

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Is there someone here that can tell me if the exhaust will accept Termio or D&D exhaust that fit the stock exhaust?
I have Termis and D&D ...I am interested in the pipes but want to know if they fit what I have or if I need specific exhaust cans for the Sill
The SilMoto (SMI) exhaust is compatible with the OEM system. So the SMI slipons will fit the OEM headers, and the OEM cans will fit onto the SMI headers - so you shouldn't have any trouble with your Termis.
 

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Some stuff I wrote for a a friend of mine....

My 2 into 1 on the Frankencati works pretty well and has now been copied on about 6 or 7 bikes on this forum all with good feed back. While not developed/tested on the dyno like my bucket pipes I think It works pretty well.

4 stroke exhaust design is much simpler than 2 stroke design because you are not having to concern yourself with creating back pressure. In a a four stroke design the only back pressure consideration is t have as little of it as possible!

Four stroke exhaust are optimised for extraction effect, where one cylinder's low pressure wave in it's header helps create a well timed low pressure point to help suck out the gases from another cylinder just as the exhaust valves in the other cylinder opens.

In a typical exhaust system there will be several low pressure waves reflected back to the exhaust valves. The first one will be where the first inter-conection point between headers occur. There will also be a reflection from each point the exhaust diameter changes, such as the entry to the muffler and also a reflection point from the exit of the slip-on to the big wide world. Multiple reflections like this mean that you have the extraction effect happening across a number of rev points.

A small difference in length to these reflection points will shift the revs at which extraction occurs. Easy to see this on a dyno with a single cylinder bike if you make a long header and then just cut 25 mm off it in between dyno runs and observe the shape of the torque and hp curve shift. I observed this, and a similar, but even more pronounced effect when I lengthened and shortened the inlet tract on my bucket with my variable inlet length tract set up (especially if I altered the jetting to suit each length.)

On a bike where you want to create maximum power at shorter revs you need to have the reflection points closer to the exhaust valves.

With an even firing 4 cylinder or parallel twin it is easy to create an inter-cylinder extraction effect on all cylinders.

With a even firing 4 cylinder the interconnection (crossover or merge) points for inter-cylinder extraction are quite close to the exhaust valves as the firing intervals between the cylinders is much less (half) that of an even firing twin cylinder engine and this makes the packaging on a four cylinder bike easier to achieve. If you look at a modern high revving Japanese 4 cylinder bike, you will see the merge points are on the down pipes quite close to the exhaust valves.

All else being equal on an EVEN firing 2 cylinder the merge points will be twice as far from the exhaust valves. If you look on a parrallel even firing twin cylinder bike, the first merge/cross over point will typically be under the engine comparatively quite a long way from the exhaust valves.

HOWEVER with the uneven 270 and 450 firing interval on a V-twin Ducati you can't create a inter cylinder extraction effect to BOTH cylinders with equal length headers of course.

Here is the thinking I went through when I designed the Frankencati 2 in to 1 system....

On a Ducati twin with it's uneven firing interval you could create a milder extraction effect to BOTH cylinders with two interconnections (A merge and an earlier interconnection pipe for example each timed to suit the firing interval to the other cylinder) and it appears that Akrapovic did attempt exactly this on one of their exhaust systems for the earlier air cooled Multistrada. (Search the internet and you will find pics of this system.)

While it is not simple to create an inter-cylinder extractor effect for BOTH cylinders to suit the Ducati uneven firing order, you can tune the length of the headers so that the low pressure wave reflected back from the end of each header would help extract gases from it's own cylinder (self-cylinder extraction as opposed to inter-cylinder extraction, for want of better terms). When I looked at doing this, the calculations suggested the length of the headers need to be quite long to achieve this at the revs of interest and packaging long enough headers on a V-Twin Ducati to achieve this is problematic. For this reason I made the headers on my 2 into 1 as long as possible. If I still had ready access to a dyno I would be keen to make up a few variations and test them back to back on the dyno as I did with my bucket pipes.

Everything is just theory and pub talk unless you make multiple variations and test and measure on the dyno.

I tested 9 exhaust variations of design and lengths on my bucket before settling on the current pipe...and now I am changing the cams which will change the valve timing so I will need to go and make up some more exhausts to test to optimises for the new cam timing.

The overriding reason in the end that I opted for a two into one system for the Frankencati is that the one clear and irrefutable advantage of a two into one system is that you save a lot of weight!
 
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