Is finding a used klx 300 exhaust worth finding over a q4 system with a 351 kit? I want quiet as i can get

 

I can tell you the 300 exhaust is definitely quieter than any slip on I've ever heard. I will also tell you one of the hop up tips for a KLX300R was to put a less restrictive exhaust on them. It's kind of a catch 22.

 

i have the stock 250 on it now, just to open it up slightly

 

300 can't hurt if you get one for a reasonable price.

 

would the current jetting work or should that get richen up

 

I doubt you need to do anything with the pilot, but maybe the needle and main if it increases flow enough to need it.