I know about absoutly nothing about carbs. What good does rejetting do after installing new exaust?  I installed a V&H pipe, other than a the louder noise and a decent increase in speed I don't notice anthing diffrent, other than some popping noises when I downshift hard.

I know this sounds like a stupid question, but you gota' lean somewhere... :dunno:

do I really need to say it.........  use the search function.  
broken down simple style, the carbs cannot provide enough fuel to run properly with stock jets, so you need larger ones,

more gas = more power

Also leaner = hotter, and that = badder...
You might run fine, heck lean bikes make better power, but it runs hotter and if its leaner than even that, it starts to make for rideability issues... like bad starts when cold, then it sometimes lean surges, etc etc... Also popping is an indication its lean. And they are lean enough right out of the box... so pipe makes a bad situation a bit worse. I'll go up 1 size upon mains and 1 upon pilots and 1 #4 under needle, and 3 turns on mix screw if allyou did was pipe. that compensates for stock leanness and the pipe.
Cool.
Srinath.

If it's not broken don't fix it.  
I re-jetted when the bike started to run lousy at about 14,000 miles.  
If it was not for that I would not have re-jetted to this day.

I have re-jetted my bike w/ the stock exhaust and the power gained was fairly substantial for a .5mm change in the jets. Top end was night and day. and the 40pilots realled helped when I took it out in early march and towards september/october when you get a little bit of frost on the ground.  for your $$$$ re-jetting is probably the best boost of power and after modifications it becomes essential...and besides if you have an older style GS the carbs probably need cleaning...I might have gained more power just by cleaning out the carbs on my 94.... :mrgreen: