yes.. i took it off and it didnt run right

 

You sure your jetting is correct? Seriously, a stock Raptor should beat the PRedator in a drag, your piped raptor should eat it up. If your jetting is correct then does your bike do anything weird? Big vaccum leaks somewhere? If your bike is 100% perfect then something is very very fishy.

 

You just found your problem. Raptor's need air. And lot's of it. Toss the lid, cut out all the rubber shrouding in front of the airbox (to make a clean path of airflow), and go to a 170/175ish main jet combo. Losing to Predator's will be a thing of the past. The top end is were YOU should be pulling away, not the other way around. Also, I'd get a different pipe as well. The FMF's are known for being restrictive.

 

All I hear is how bad the FMF's suck actually, no flames intended to anyone. My Yoshi worked great, I had a full system with proflow kit and dynojet jet kit.

 

the only thing i didnt do was turn the fuel mixture screws cuz people told me it wasnt necessary

 

I can't tell you how to fix your bike, sorry but answer this. Is your bike faster than without the pipe? Is it running better in ALL gears in pipe form vs. stock form?

 

no.. i seem to of lost top end.. the banshee that i could almost beat is now pulling away!!

 

Then I imagine you are running out of fuel up top. You are probally lean or something. If you are slower than before then your bike is most likely fine but your tuning is off. Your bike in stock form should beat that predator, now if your bike is slower now, then it makes sense why he beat you. Who rejetted the carb?

 

I haven't seen a rappy beat a pred stock for stock yet.....
My cousin has a pred and I KNOW it is stock......and I have raced 4 of my friends on his pred and beat them all.......(stock rappys)
now when you get to the piped and jetted rappys.......the doesn't have a chance.......
I had my gutted stock pipe......equal to a cheap slip on.....loL
and it was jetted......with no lid.....and I was leave'n the predator off the line, through the gears, and top end.......

 

i did it my self... in the left carb i have a 146 and the right has a 148