just bought a m4 full exhaust for my 99 900RR and was wondering if this was a good purchase?

i plan on combining this with a factory pro jet kit and a timing advancer will this give me more power?

 

Im not sure about the M4. I had a full V&H SS2R on my 99 with a K&N and dynojet jet kit, no timing advance -1 up front and it was fast as ****. I have not ridden a 900RR that ran as good as mine. I know they exist, just not in the circle of people I ride with. I would go for it. I have heard the stock system is quite restrictive and even a slip on is supposed to be good for some hp.