Exhaust questions and my neighborhood muffler shop

[TeBo]

I was thinking of buying an exhaust for my GS500, but it seems like there's nowhere to find one.  I don't want a slip on, cuz I want the loud to mean something more than to irritate neighbors.  I was thinking, If I took a slipon exhaust to a mufflershop, and had a whole backpipe redone, would this help??  I was thinking along the lines of just making the header and pipe wider in diameter.  Any suggestions on how wide my pipe should be?  maybe anyone w/ a Yosh or V&H full exhaust know how wide their backpipes are?  thanks for the help

[The Buddha]

OK V&H and Yosh are a bit bigger dia than stock... however they have no cross over, which might be significant ... The restriction to flow in the stock headers is all in the muffler... The headers can flow 2-3 times what the head/exhaust ports can flow without significantly affecting the rate. Hence a slip on and a full system are the same in a stock bike. I have run them back to back on my bike to compare, and the slip on was just as good. The best ever can I have had on the bikes... I have had a Yosh and a V&H on it as well, but The D&D I had on it with a GSXR D&D slipped on stock GS headers... was the best. Quiet at low rpm, and ear drum ripping loud at high revs, and it made more power by the seat of the pants dyno and let the bike spin up higher rpm up on top. It was the largest diamater can I even had on it as well... so that is the key. Big ass can.
Cool.
Srinath.

[chinox22x]

get a yoshi RS-3 oval can


get it welded there...sounds nice.

[The Buddha]

The oval cans are great quality... and that stainless tubing is great, but they are very long and larger in diamater than has to be... Short and large ID is best.
Cool.
Srinath.

[TeBo]

So on a pretty much stock bike, I'd be better off w/ a slipon? (not really planning on blowing hte bike out of the water, maybe a filter or a vstack.. not much more).  Would it be good if I got a slipon from another bike or a slipon for a GS500, and took my bike to the muffler shop and got slightly bigger backpiping or headers?  Or should I just leave the stock pipe, and put the slipon exhaust on?

[The Buddha]

Aftermarket can... the non flanged slipon type works best.. short length is better and larger ID is better. Katana 600 cans have been the simplest to fit and cheapest to getoff ebay ...Yosh or V&H is likely to be cheapest, with the quality edge going to Yosh. Round is good and as is aluminum as opposed to stainless.
Cool.
Srinath.

[indestructibleman]

it's worth noting that while a freer flowing exhaust may increase HP, it often does so at the loss of torque.
all that back pressure is in there for a reason.

cheers,
will

p.s.  this is just a general comment, i really know nothing about aftermarket exhaust for the GS.

[conradvr]

it's worth noting that while a freer flowing exhaust may increase HP, it often does so at the loss of torque.
all that back pressure is in there for a reason.

cheers,
will

p.s.  this is just a general comment, i really know nothing about aftermarket exhaust for the GS.

Back pressure isn't there for that reason!  Besides how can you increase HP and lower Torque at the same time?  Sorry but I hate general comments that are so friggin wrong, unfounded or incomplete.  Please go do some study on exhaust system design before posting comments on the matter.  Try starting at  http://www.proficientperformance.com/tech_back_pressure.htm

Back pressure is a negative side effect of having to silence the exhaust noises in the 1st place - less back pressure is better, but you have to also consider other factors such gas velocities in the pipe etc.  Most 2-1 and 4-1 systems are designed to use the exhaust pulse from one cylinder to assist in the scavenge of the exhaust gases from another cylinder, these systems are tuned to for a particular rev range ie. more power/torque down low, midrange or topend.

[The Buddha]

it's worth noting that while a freer flowing exhaust may increase HP, it often does so at the loss of torque.
all that back pressure is in there for a reason.

cheers,
will

p.s.  this is just a general comment, i really know nothing about aftermarket exhaust for the GS.

This is sorta right... very very vaguely generalistically and incomplete... but right...
Back pressure holds in mixture and in fact has exhaust gas still sitting in the cylinder... that makes for a mix that is more completely intact... meaning you haven't lost a small part of the intake charge into the exhaust and exhaust gas sitting in the chamber is hot, and it will not burn... so it helps combustion... especially at low rpm... so it makes more torque... and feels like its richer than it actually is... and in reality its lean so it feels right.
Lose the tight ass can, and the back pressure goes, as does the inert hot exhaust gas in the chamber when the exhaust valve closes, and what is worse... depending on how much over lap there is in cam timing, you lose a bit of the intake charge. So that makes a lean mix, that is also likely to burn incompletely and no inert hot gas to heat it up ...
So what should we do to make up for the loss in intake... add some intake... aka rejet. So a pipe and rejet will compensate for all that, with the only expense being a little intake charge loss, and exhaust noise. So your gas mileage suffers a bit, and all is normal. The payoff, is a cooler engine... no hot exhaust heating up the chamber, quicker revs due to back pressure not being there, more power due to the exhaust stroke not sucking power out pushing against a crammed up pipe ... and at higher revs a lot more power, cos it revs up higher up on top. BTW a stock GS is jetted too lean in the US bikes anyway to pass EPA... back pressure or no back pressure... I'd go up 1 size on the mains and 1 on pilots and a washer under needle.
Cool.
Srinath.

[indestructibleman]

sorry, i was in-exact on my terminology.  i should have said that you often sacrifice low-end power for high-end power.
the engines are designed and tuned to produce the best power across the rpm range while running with stock back-pressure.
this is more an issue with newer sportbikes where the manufacturer's engineering team has done everything possible to get the best power curve out of the stock system.
i understand that the GS runs lean to begin with so it doesn't really have an ideal stock setup.

cheers,
will

p.s.  i'm just paraphrasing Jack Mac, the most highly certified Honda Technician in the country.

[The Buddha]

The stock is not optimised for max power or torque ... its still strangled by epa. Its optimised for making as much power as it can while still passing EPA. After all that is done and the bike gets out on the street... the aftermarket screws around with it and makes it better. Our bikes are so far off the optimal anything... that anything we do, even a homemade chopped up lousy ass can is an improvement.
Cool.
Srinath.