I have two exhaust pipes and I decided to put one on with holes drilled in the end. It sounds ok and I may keep it on for awhile, but Im worried about being to lean. I think there are about 5 or 6 holes each being 3/8 or a 1/2 inch in diameter, Ill confirm tommarow. Do I really have anything to worry about? If I do, is there any way to richen up the bike without buying a jet kit? Thanks.

No one that has ever done the drilling you speak of has ever mentioned any change in performance-good or bad- so you'll likely not have to do anything to the carbs...unless they're stock jetting then even if you don't drill (or haven't drilled) holes if its a US bike you should rejet, but that's for another thread...

Drilling holes in the end doesn't actually increase airflow - the restrictive part of the exhaust is already there. So no, you shouldn't rejet because you drilled some holes in the exhaust - but as Pablo mentioned, the GS is jetted lean from the factory and you might want to rejet because of that.

I beg to differ. If you get a long drill bit, and drill the first baffle as well, it actually should be less restrictive. Maybe not much, but some at least.

The stock header pipes are very small ID though, which limits what modifying the muffler baffles can achieve, or even putting on another can for that matter.

I have a Yosh full system on one bike and stock headers and slipped on can on the other. Yes the yosh headers are larger in dia but I dont believe it makes any difference. The stock headers are big enough for the rpm range the motor is capable of. Yea there may be specific aspects like how quick it spins up or how much power it makes at a specific rpm that may be different between the 2 but for most street users and for jetting purposes stock headers flow enough to let the motor do what it wants. The stock can however is another matter. The can is the most restrictive part of the bike and easily the biggest impediment to performance.
Cool.
Srinath.

It has 6, 3/8 inch holes drilled in it. I didnt do the drilling so I dont know how far they went in with the drill bit. Also I might try to cover up two of the holes but I dont know what to cover them with, any suggestions? Thanks.

does it look like this:

http://www.bikepower.net/gs500e-power/gs500e-power.htm

[click on modification manuals>engine mods>stock exhaust mod>]

Yes, it has the ones on the outside, but Im not sure about the ones going all the way to the front.

Quote from: seshadri_srinathThe stock can however is another matter. The can is the most restrictive part of the bike and easily the biggest impediment to performance.
Cool.
Srinath.

From my dyno tests on my race bike, I'd have to disagree. The exhaust can doesn't make much difference even after you get rid of the airbox, which is the biggest bottleneck.

The gains on the exhaust side, after freeing up the intake, are pretty small until you do some porting and bump the compression.

Until you get pretty radical (much higher compression, extensive porting, wilder cams), the exhaust sytem doesn't make much difference, and then the stock header diameter is and issue.