So, I've only ride 2500km on my 2014 klx250s, I'm planning to get and aftermarket exhaust and the uni air filter when I hit the 3000km mark. I want to get a good performance but no excesive noise, So apparently all reduces to the FMF Q4, but I can't find any dyno chart on the fmf exhaust while Twobros has their own charts on their web, also I think the twobros It's more good looking

I know there are a lot more exhausts on the market and almost every brand sell their especifics db killers. I want to know which ones are you used? Is it worth it? for example getting the twobros full system with a p4 power tip, how much the power will be reduced?

 

Obviously, you know an aftermarket pipe is going to be ALOT louder, but I've personally owned a Q4 (crf230f EFI though) and a PC4 on my 2013 KLX250s. Which is louder? The PC4, but not incredibly louder. I got the PC4+Megabomb on my klx250s and it lowered the same by a bit. If you're concerned about headaches or cop trouble with the loud noise, through a helmet it's not that loud ,it's just a beautiful rumbling. I live in a small town with a lot of older people (Population of 8,000) and I ride my bike high rev all day (6000 - 8000 RPM) and never got a single complaint (except wheelies on the street LOL) about noise. I woudn'lt be too worried unless you ride passed 11 at night.

The two bros is MUCH louder than the PC4 or Q4. Just the slit on no performance gain or minimal I find at least.. spend the extra get the full system, jet kit, air box lid removed and you've got yourself a start to unlocked some power. Then big bore, then cams, then debts.. We all got that addiction

Enjoy. sorry for my bad english, frenchy here LOL.

EDIT : You asked with the full system how much power you'd LOSE, you'd win an easy 1 HP at least! More air more power my friend just make sure you re-jet if you get the whole kit

 

Ive been using the PC4 with the quiet insert now for a year, no complaints and i love the sound.

 

Johnatan, while there is not a "quiet" aftermarket exhaust ( compared to stock ) the full FMF ( megabomb + PC4 ) or just the PC4 should be quiet enough if you keep your rev's low. Mine is, just as is Daren's.... The noise increases greatly when you wind it up though... I am not yet convinced that the Megabomb shows performance increases worthy of its' price - You can judge my dyno charts for your self. I have not tested the stock header + PC4 yet but that combo may be ideal for maintaining TRQ down low along with a better top end. You have to remove (and in my case destroy) the slip-fit gasket to get the PC4 onto the stock header - so I haven't done that yet...

Your real problem will be with jetting after your slip-on and Uni purchase. You are shooting for a WOT AFR between 11.8 and 12.8:1 for max power. This all depends on your elevation and intended riding elevations. Read our threads and posts and you'll decide how you want to proceed with jetting..

 

For the cost of the basic uncorking mods, I could have had a 300 big-bore kit (not figuring in installation). Had to do it over again and I think I'd go with the BB351 before anything else.

 

klx-vn, basic uncorking is a DynoJet Jet kit and a slip-on. Go with a DG-R slip-on and your total costs are right at $210.00 and you'll get 20-22hp ....

 

You're right. I included air filter and snorkel. And I've always been partial to the sound of Yo$himura for some reason so what I've got in is close to the BB 300cc kit. Best bang for the buck?

 

I agree on no performance gain for megabomb, 300$ for a header kinda crazy. I should of bought the cheap ebay megabomb knockoff. None the less, it looks cool, no? Lol

 

LOL, I'm very bad at english too, I'm Colombian . Maybe I didn't writed properly, My question is if I ADD some DB KILLER, like the p4 power tip from twobros into the full system, Is the power loss noticeable?

No way, That's a hardcore mod for me, I don't want to expend that amount of money, and that's almost changing half of my brand new engine for another one... So, nope!

Don't forget my point, I want a slip-on as quiet as the fmf q4, I'm just wondering if there are another one like that, or If for example I got the DG-R and ADD a DB KILLER It will worth or not, making a balance between the power loss (bad) and the noice loss (good if getting close to the Q4)

How about the regular powerbomb worth it or not?

 

I think a klx300 muffler has a bigger outlet and is way quieter than my FMF PC4. I believe I have a stock 300 muffler on mine. If not, the previous owner must have enlarged the hole. It makes more low rpm torque than the pc4, but doesn't rev as high or freely.