Quiet cores

The wr426 I just bought has a Pro Circuit exhaust system on it and I am tring to quiet it down some (to help please the neighbors). My question is if I install the quiet core will I have to rejet the carb? or won't it make that much difference.

Yes, you'll probably have to rejet.

You're better off just getting a new quiet design muffler.

I had a T-4 on my old bike and the quiet tip knocked off 2 db at 3750rpm (test rpm). It was still loud at big throttle openings even though it was technically legal.

My friend had an older style T-4 on his XR 250R (huge core/megaphone midpipe) and the quiet tip from my muffler actually made his bike louder and made the sound "tinny"

That same friend rides an XR 600 now with the latest T-4 (cone style end cap) and its actually pretty reasonable at idle and small throttle openings but its still deafening at big throttle openings.

I think the quiet tip would be a waste of money if you're trying to do the stealth thing.

I wasn't going to buy a quiet core I have left from the ttr.You are right it didn't seem to make much difference.

I have the stock exhaust on my 02 and run it open and with an after market insert with out having to rejet. But then again I'm running a JD kit.

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