Is there a reason to purchase an aftermarket exhaust. Is there any horsepower gain with a 4-stroke. Sorry for the ignorance, first 4-stroke. Been a 2-stroke guy my whole life. And if so, do i need to replace the head pipe as well or just the muffler/spark arrestor.

FMF is just one of many aftermarket headers/silencers, here is a link to their dyno charts to see the gains:

FMF's dyno charts

If you're riding a WR, there's HP to be had in changing/modifying the pipe. The cheapest and easiest method is to pick up a Vortip from www.finelinesuspension.com The Vortip is an insert that replaces the stock plug in the end of the WR muffler and triples the exhaust flow while keeping the sound reasonable. Price is less than $70 incl. shipping. For more HP (and more money) there are a number of exhaust pipes and headers available, all providing more power than a Vortip, but also more noise. Keep in mind that changing the exhaust without rejetting,removing the airbox cover and removing the gray wire will not provide a lot of gain.

There is significant improvement to be had if you feel like spending the money. The head pipe is more money but also a bit more gain. dmp437 had a good point to keep in mind, if you go for a pipe, make sure you do the other free mods also. Otherwise your performance improvement will be minimal.

Well then one more question, the FMF Q exhaust? Is the horsepower loss worth it, or is it one of those .005 dB differences where you never notice it. And furthermore, who do you quiet it down for, yourself or others?

Any recommendation on an exhaust would be appreciated.

And to Ca riders out there, Jetting. Any recommendations. Sac Valley up to Sierras (20 to 4000ft). '02 wr250, baffle out, air box modified, blue/grey wire gone, throttle stop out.

"who do you quiet it down for, yourself or others?"

If you're in California, I understand in 03 you need to be under 96 db(?). We all need to help in the quieting down department...

To answer your question, you're quieting down for yourself and others - probably mainly others since when riding, you don't notice the noise as badly as the person on the sideline.

FMF Q owners can answer you better, but I think they like their Q (i.e. a compromise in power/sound) but not sure what the db level is for it. My FMF Power Core IV is loud and obnoxious versus my Vortip/stock silencer For closed tracks/parks I plan to use the PC4, but for the forests I'll probably have to use the stock/Vortip setup.

Thanks for the advice. For now the Vortip is the winner. I'll see how the laws go in '03 and then decide on a new setup.

Has anyone been able to compare the Big Gun quiet series with the FMF Q? From some of the post's I have come across it looks like the Bug Gun may be able to produce more power without the noise. Mike at Bug Gun also told me that the quiet series only loses a little bit on the high end vs. the race series while maintaining a 96-97 dB level. Is that possible? He also told me that they are almost ready to release a quiet insert adapter for the race series pipe that decreases the noise level by 10 dB without any power hits. He seemed really excited about it. Does any one buy into these performance claims? Does anyone have the quiet series that can post noise levels and it's performance. Any info would be greatly appreciated

White Bros. E-Series with quiet core insert?? Who has it, and is it worth the money. Got a good deal on one, deciding whether or not to buy it.