Jetting question on my 400ex

[Swags04]

I got my quad with a K&N and a Pro Circuit Muffler On it. It was rejetted, and ran great, no flat spots..

I sold the pipe and purchased a full White Brothers Exhaust system, my question is will I need to rejet for compensation of the head pipe? I was told a 155 and 42 Pilot, but i didnt want to put new jets in and pay for them if the ones in (which i dont know the size) are good enough..?

Thanks!

you should be ok. that is what i am running in my 2000 400ex witha big gun full race pipe and k &n filter...just remeber that even tow of the same pipes(big gun and big gun, for ex) can require different jetting so i would do a couple of plug chops after the change over to be safe

[coolex]

should be ready to ride because ur not really making it into a eaven more high flow exhaust its just a little diffrent for a little gain but ur good to ride