luckily someone else did my jetting for my raptor but we are now working on a different one. we put on a fmf ti4 slip on with stock air filter and box intact. will we need to rejet it or not. if so how big. I appreciate all help someone can give me.

 

If the previous exhaust was the stocker, you will need to rejet. If by some strange chance you don't have to, return the exhaust, because it won't do you any good. A slip on should give you more air flow through the engine, therefore you need more fuel(bigger jetting) to go with the extra airflow and make power.

 

Well we got the pipe on and started to rejet the carbs untill we realized that he bought the wrong jets. but it worked out because he got mad and sold me the pipe for 50 bucks because he now wants a full hmf. It will be on in about an hour and rejetted.