Just picked up an 07 foreman and have already put in jets and a clutch kit. I have an old curtis sparks pipe left over from my raptor. Can I just weld this on and still get good performance gains or do I need a pipe made specifically for my quad?

 

The results of putting a pipe on a machine that it wasn't designed and tuned for would be anybody's guess.

If I were you, I'd craigslist your leftover part, and either leave the exhaust stock or snag a pipe designed for the Foreman...

Congradulations on the new Forman. Have fun with it.