I am having trouble deciding what exhaust pipe to purchase..it's between White Bros. E-seris or Pro Ciruit T-4...and I aso have heard that the cobra pipes a good stuff...I have a 2002 yellow 300ex and do mainly trail riding...I know I have to rejet when I get a new pipe and also plan on getting a K&N filter...what pipe do you suggestion between these?

 

Both the White Brothers E-series and the Pro Circut T-4 are good pipes. I don't know what the exact HP and torgue increase is for the 300ex, but I am sure that it is probably pretty decent. As for the Cobra, my cousin had a Cobra Pipe on his 1988 LT 230 Quadsport. It sounded awesome. It was really loud, I mean really loud. The problem with the Cobra is that it is a steel pipe which means it will rust. As for me, I no longer have a 300ex, I now have a 400ex. When I had my 300ex I had a DG RCM Steel pipe on it. I don't want to say that it was the best pipe for the 300ex, but it was pretty decent. The DG that I had is more of an economical pipe kind of like that Cobra pipe. It was made out of steel and rusted. I had to take it off and scrap the rust off and then paint it with Fire Proof heat paint several times. My guess that you would run into the same problem with the Cobra pipe. Which is why I would go with an alloy pipe like the E-series or the T-4. So I think that you are in the right market. However in my opinion, you might also want to consider the FMF Powercore IV pipe. I am very pleased with the performance increase that it did to my 400ex. I know that I have a whole different machine than you, but I would bet that the FMF pipe would also be a good choice for the 300ex.

As for re-jetting the carb when you put on the new pipe, you don't necessarily need to re-jet it. What I would do is put the pipe on and then take it out and run the crap out of it through every gear. If it "bougs down or back-fires" then you will have to re-jet. If not, then you should be okay. However if you plan on getting a K and N air filter, I would recommend that you re-jet your carb.

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