So, a few months ago I got a sweet deal on a 2009 klx250sf. I really like it, but of course I'm already thinking of what upgrades to do to it next winter. It's 100% stock right now. Probably going to do the 351 big bore kit, new cams from webcams, and new exhaust. Any recommendations for the exhaust? Also, since I'll have it all torn apart anyway, should I go with a new carb?

 

I have the fmf q4 and megabomb and really like it.

 

the Powercore 4 makes a huge difference when you have the 351. absolute instant throttle responce with that set up and jetted carb. bike scared me when i took it out for the first time with the exhaust added to the 351

 

I love my KLX300 header and muffler, it makes the KLX sound like a thumper (not a sewing machine) and is still quiet. It took some patience on fleabay to find one. They are still out there.
I had a FMF PowercoreIV. People definitely heard me coming, from a ways away, and it gave me a headache from how loud it was. If I didn't ride off road I might have kept it, it did sound badass.
You don't have to wait for winter...
You could put on a new muffler, air filter, and re-jet, right now...for a little more performance.

 

yeah noo need to wait for winter i did my big bore on a weekend last summer.
and yeah the PC4 is loud when you really rev it but you can still quietly drive up the street if you keep the rpms low, its nothing like a Harley or anything lol there is also a quiet insert that you can get and even with that you are supposed to get more power then the more expensive q4 lol

 

dg exhaust 100db, $150.

 

If you want it to remain quiet, go with FMF and the PC4 with the insert or the Q4.

if you don't care if its ear splitting loud, than anything else will likely be fine.

 

Well, there are a few reasons I'm waiting until winter. $$$ being a big one. I was already leaning towards fmf, so I'm glad to see it recommended.

 

+1 powercore 4 with quiet insert made all the difference.