white brothers R4

[chrisc]

anyone ride a 400ex with a r4 on it. does it really have more noticeable power over stock? or is it just louder. I have asked other people and they say yes, but if i had just spent 250+ on one I would say yes also. so give it to me it straight .

[remlapr]

If you have a stock 400ex, then YES the R4 or any good slip on will give you more power! You should also buy a better filter and re-jet at the same time though to maximize the better exhaust flow. If you are saying you already have a slip on and are wondering if going to an R4 will make a big difference, probably not unless you have a really crappy pipe now...