My friend has a 1999 honda 400ex with a Big Gun full exhaust system. He says his ex is faster than my z400, which has a White Brothers R4 slip on exhaust and a Uni air filter and no lid. Please tell me which is faster, he thinks becuase he has a full system that his is faster, somebody besides me, needs to let him know that 400ex dont respond as well to mods than Z400's and that his big gun system isnt the greatest exhaust in the world...

 

Go race him and find out!

 

have you raced him yet? that will tell who's faster.
the Z is a lot better for mods than the 400ex.
I've raced some 400ex's and have been beaten buy them
it all depends on what mods are done and gearing
but having a full pipe compared to just a slip on may give you a
little more hp but you should be able to beat him racing
the Z is a faster quad than the 400ex with both stock

 

if you both know how to ride you should take him easily

 

i don't care if you belive me or not my my stock 400ex smoked my freinds z400 and he has a full yohimura pipe on it i have beat a stock yfz 450 twice drag racing on pavement but i was beaten by a 400ex with full fmf pipe and 12000 rpm rev limiter by 4 bike lengths my engine 100% stock

 

If he's jetted/tuned properly and knows how to drag race his 400EX then it could be very close. Theres no guaranteed winner with these two although the odds are in your favor. Good luck!

........And no, he shouldn't be saying he's faster than you without actually racing you.