Hi Guys,
Anyone here had any luck modifying the stock exhaust to breath a bit better. Living near & riding mostly in Quebec I would prefer to keep my exhaust as stock looking as possible, but with Mr. 351 and Bills Pumper now in the stable I am sure I could release a few more ponies opening up that straw like end cap, not to mention gutting the Cat material a bit. The police in "La Belle Province" are a little sticky about modified exhausts, especially if they are very loud. Any advice would be appreciated as I picked up a used Muffler to practice on.

 

It you go back a ways, you'll see when the '06 came out, riders started taking a 1/2" drill bit to the pea shooter exhaust. They gained some noise, but I think its fairly well agreed there was no real performance gain. And it ruins the spark arrestor.

Look for a KLX300 exhaust system if you want to maintain the stock look and gain some performance without a large increase in noise.

 

I had the same question before I ordered my Q4. From what I've read, the 300 and 250 exhaust are the same (not the header), with the exception that the rear bung can be removed on the 300. Why wouldn't it work if you drilled out the rear baffle and put a larger opening (with cover and small pipe) that is similar to the 300? Keep all the other baffles and spark arrestors in place though. I understand the need to rejet and get the 2152 kit, but why wouldn't you get similar performance as the 300 setup? Maybe it's a noise issue. I'm sure those that are knowledgeable will speak up

 

I believe the KLX250S has a Catalytic Converter in it and the 300 does not.

 

On my KLX300, I removed the end plate, allowing a much better exhaust flow. It was sound checked at an OHV park and read 93db. 96db is the upper limit around here on public land. It also has an aftermarket head pipe.

Ride on
Brewster

 

Anyone know if the 300 exhaust is noticeably quieter than a 2 bros or q4 without losing performance?

 

Uncorked, the 300 system is more quiet than a PC4 or a DGR + stock header, according to my ear.
The 300 system will permit power levels same as stock header + slipon.

I do not know what header will work with the 300 can - Apparently Brewster knows of one..

 

I know a guy that has a complete 300 exhaust for sale, $75

 

ITHAPPENS, if you find a good mod for the stock 250 can, please share..

You really should put a full 300 system on your 351 with a large end cap - available on Ebay.. Better yet, add a larger dia. performance header to the 300 can..
Here is a thread and a excerpt from it - '09 KLX250S - DynoJet Done - Pipe/Header Help - KLX/KLR 125/140/250/300 - ThumperTalk - "The FSW header will fit with the stock KLX300 exhaust"

 

Here is the FSW page - FourStrokeWorks - quality products and services for four-stroke motorcycles