The only thing i have done to mine is took the little screen out of the baffle. I was wondering about grinding the welds inside the head pipe(I have heard people mention this before)I was also intrested in mods for the stock silencer. Yeah i know get and exhaust system. But right now the R-series promeg is to rich for my blood. Thanks for the info.

 

I've got a R4 w/stock head pipe and I'm going to grind the welds off. It's bound to help some. There is 10-15% restriction with those welds. They gotta go.

 

I have talked to a lot of engine builders and they said that the stock headpipe is fine, but some say it isn't. I think if you could grind down those welds then it would flow a lot better. I think I am going to get a pro ciruit silencer and just use and modify my headpipe rather than spend $500 dollars on the DMC. Anything is better than my Big Gun full system.

 

I heard if you take out the spark arrester and cut out the screen it will give you a little more power. You could even just take the whole spark arrester and not put it back on.


2001 Red 400EX SporTrax

 

Where are those weld in the Stock pipe that everone keeps talkin about? Are they where the pipes bolt to the head on the inside, where?

 

The welds are inside the head pipe where pipe meets the exhaust ports. There is a ridge that sticks up about 1/8"-1/4" all around the inside of the pipe and by grinding them away will allow pipe to flow better giving more hp by theory.

 

LDJ, stay away from the T4 Pro-Circuit, it is poor quality, welds broke on mine, you can't bolt up your heat sheild, it looks bad(ugly headpipe) and I never could keep it from melting my clutch cable, WB R4 is the best thing out there!

 

I am just going to get the pro circuit silencer and keep my stock header, I think.

 

Who ever here is planning to remove the spark arrestor: make sure you get a big ole' John Deere sticker for that quad. That's about what it'll sound like. If your gonna do any exhaust mods just save your money and get an aftermarket muffler.