With all the exhaust systems on the market for the KLX250 its becoming hard to decide what system will work best with a jetted KLX250s with standard bore.

Ive read good things about the BigGun system and the price seems pretty reasonable for header and muffler combo.

Then we have the Powerbomb and Megabomb FMF header with a couple of muffler options from FMF.

Last the almighty Two Brothers complete system. Expensive but worth the $$?

Or you could just drill out your stock baffle and save the money but wouldnt look as cool.

How do you guys feel about the exhaust setups you have?

 

I am very happy with my FMF Q4....plus a few other goodies that I installed with it! But even if the bike was completely stock I would recommend the Q4.

 

Im happy with my TwoBrother slip on w/P4 but it can be a bit loud.

 

Personally I think all you need is a slip-on. Any one of them. Open up the intake and re jet of course.

 

Thats what Ive heard from some sources. Some even say you hurt your low end torque by using a header vs the stock pipe(loosing exhaust velocity). Im interested in seeing how the powerbomb and megabomb expansion chamber affects the power band.

 

I agree. I'm not really sure how an aftermarket header would benefit a single cylinder vehicle of any sort. There's no manifold where a few pipes join together as in a multi-cylinder engine, so the overall improvement in flow would be marginal at best I would presume. I'm no exhaust expert by any means but IMHO i would see little to no benefit of a header on a single cylinder vehicle, especially for the price some of the companies are charging.

I put on the Two Bros M7 exhaust with the P1 tip, it is pretty loud but that's why they make ear plugs right??

 

As you can see from my signature, I have the FMF Q4 and the megabomb header. I'm very happy with it, it sounds right, but isn't so loud over all that I feel like a total jerk pulling into my neighborhood at one am (I dont rev it or get in the throttle though) I'm also not worried about stirring someone to call the cops when I'm hitting the trails. I believe it's rated 96dB (stock is 80 something).

Someone above said the header is a waste... I've seen documented where guys said they lost torque with a header down low and found it harder to loft the front end after the swap. Here's my theory on this and why I picked the mega-bomb header.

1. The loss of torque is going to happen most at lowest RPM's because of the lack of back-pressure and I dont chug this motor much, I like to keep it over 4 grand.
2. The more wide open you have it and the more you get the revs up, the more you will get torque back from mid to top end. (also the megabomb is supposed to specifically emphasize aiding the torque issue in general. )
3. My ultimate plan doesn't stop at just pipe and header, I want to go big bore and i got the best deal on the package with them together, plus the package ensures good fitment (see below). The header may be premature, but it's ready for when I go big bore.

Now that i have my jetting real close, my bike is significantly faster and is pulling the front easier than it was with stock pipe and jetting. I'm quite happy with how it's running. MAYBE if I put the original header on and did the adapter to the bigger slip on I would get more torque down low and pull the front easier than I do now, but I suspect I would lose HP up high and over all acceleration and the fit is right so I'm leaving it.

As of the moment, i'm really happy with the gains from pipe and header. I also have noted that at least a few guys switched from the power-bomb TO the megabomb header, I'm guessing this is for torque.

I believe that if you get ONLY the slip on, there are fitment issues to be careful of since the length of the header varies depending on which bike you got (aussie vs US version) and many of the slip on's are the one that would be used on the KLX 300 but the US version 250 header pipe is narrower and slightly longer, which can push the muffler back into the tail-light on 09 and up bikes. I've also heard guys with the mix of pipe and stock header complain of melting their air box (I dont remember which mfg). My complete package from FMF came with a spacer and fits beautifully front to back without issue.

It would be great to see some guys that tried more than one system, but that seems unlikely on a bike that is so innexpensive to begin with. But I suspect any system will give you gains and concerns might be cost, sound/volume, legality, and looks.

My full system was around $500 from the local dealer, came next day.

Oh and i suggest buying a new head to header copper seal ring to do the job.. original might work, but is really smashed compared to a new one.

 

+1 on those thoughts. Slip on and stock header wakes the bike up. If you must spend the extra $$$ on the header, save a bit more and get a big bore kit. Much better bang for $.

 

As you ride around with your slip-on and big bore kit, just be sure to...

'Watch me wallaby's feet, mate. Watch me wallaby's feet...'

 

Watch me wallabys feed mate.
Watch me wallabys feed.
They're a dangerous breed mate.
So watch me wallabys feed.

Tie me kangaroo down sport,
tie me kangaroo down.
Tie me kangaroo down sport,
tie me kangaroo down.......[altogether now!...]

ROTFLMAO. He's from Perth too. A real "Sandgroper."