Hey guys (and gals)-- I've been lurking here for quite a while, and first off, I'd like to thank everyone for all the valuable info that you've provided me in my newbie quest for learning the ins and outs of the KLX! Much appreciated!

I'd like some feedback from those who are in the position that I soon will be. Sometime this winter I plan on having the 331bb done along with the 34mm Mikuni carb, both done by Bill Blue on my '07 KLX250. I've been searching to see what others have done as far as headers/full exhaust/slip-ons after the 331 was done. I'm going with the Two Bros. slip-on, that's definite (wish they made a full system for the KLX!) I like the Two Bros.--looks, sound, etc.--so please don't flame me about my choice; everybody has their preference, nobody's right or wrong, so please don't let this thread turn into another pissing contest about who's exhaust is better.

Anyway, I guess my specific question would be: which header should I use to fit up to the Two Bros. slip-on after the 331 is done? I had considered putting on a 300KLX header until it was shown here that they are essentially the same pipe, and would be worthless to do so. I've considered a pipe from Fourstrokeworks, but will it fit up with a Two Bros. slip-on (for the 300KLX model I presume)? Also, just how worth it will it be to change the header out from the stock 250 anyway? According to Bill Blue, he said that there was nothing wrong with leaving the stock 250 header on after the 331 was done and that the back pressure that would be created would actually provide me, if anything, with more low-end torque, which since I ride 90% off-road anyway, would actually be a plus.

Thanks in advance, and again, thank you for all the information that everyone's provided to me thus far--you guys rock!

 

300 won't fit with the two brothers, fmf powerbomb will all the 300 headers are a different length. You can leave the stock on and try it out and when you want change it.

 

The KLX250S and KLX300 headers are NOT the same. If you are going 331, go with the KLX300 header. Also, 2 Brothers does make a slip-on exhaust for the KLX300. The part number is 005-2140406V. Stick with similar stuff and you'll be fine. In other words, 300 header / 300 pipe, 250 header / 250 pipe. Hope that made sense.

I'm planning on doing the 331 kit later this year, too. My current setup is an 09 KLX250S with the stock header running a 2 Brothers exhaust. It fits great. However, when I upgrade the motor to 331 cc's, I'll need to pick up a new header AND exhaust. Actually, at that point I'll probably go with a full Muzzy setup. How's that for confusing!

 

No you don't the fmf power pomb fits the stock muffler, hmf,two brothers and fmf muffler any 250s specific muffler

 

Power bomb stock muffler here you go. I use this setup for AMA dot dual purpose rides

 

Yes, you're right. I was referring to Kawasaki OEM headers in combination with 2 Brothers slip-on exhaust pipes.

 

bailor, you'll be completely happy with the 2 Brothers slip-on. It's a very high quality canister, sounds great and provides an ample hp gain. There are many here who are running them.

 

looks like we've got a new 'muffler king' eh? lmao

if you go 331cc, you most definitely need to upgrade from the tiny oem header. if you don't, you'll be sacrificing power all over because the bike can't breathe properly. With all due respect, BB is wrong on that one. Even Roeseler said with the stock 300cc cylinder, the oem header was too small and the bike couldn't breathe properly. That's why he changed headers to a stroker header which is essentially a FSW styled header.

read this article to see just exactly what the pro says about the oem 300 headerl

http://www.motorcycle.com/products/s...mods-3510.html

 

Was waiting for you to answer but you must of been busy on a jetting thread. If the funds aren't available the stock header could be your last change. This comes from a guy that actually has a big bore. Remember INTERNET, bike stickers and magazines have alot of bs to sell thier product, some people believe alot of this crap.

 

For what it's worth, IMO, the header does make a very noticeable difference. I have a FSW header and went back and forth between it and the stock header with both my 300 and 331. If you are spending the money on the big bore, carb, and exhaust I think it would be wise to factor in the header as well.