I HAVE A STOCK 400EX EXEPT FOR A K&N FILTER AND JET KIT. I WAS WONDERING WHAT WOULD BE BETTER, THE WHOLE PIPE OR JUST THE SILENCER.BECAUSE I HEARD IF YOU GET THE WHOLE PIPE YOU HAVE TO DO STUFF TO THE MOTOR.WHAT WOULD BE BETTER BECAUSE IM NOT GOING TO DO ANYTHING TO MY MOTOR.PLEASE HELP ME. THANX

 

First off you dont HAVE to do stuff to your motor with the full kit but the performance gains over a slip on without any additional engine mods are appx 1-1.5hp due to larger header(higher flow) and thats at the high rpms,but with a slight(barely noticeable) loss of low end torque compared to slip-on on a stock engine.If you dont plan to due any engine mods at all the stock header with slip on will be more than adequate.However I do recommend getting the full system anyway.The slight loss of low end torque with full system compared to slip-on w/stk header is so minor compared to the quicker revs and stronger top end the full system gives.A higher rpm rev box will also compliment the aftmkt exhaust due to motor breathing and revving better.port matching intake and exhaust help as well.have fun