hey there i was wondering what would be a good pipe for my 2003 yz 125i want a good racing pipe for the track and im not sure whats good i heard the pro circuit is only good for kawasakies so what ever you choose please say why and whys it good thanks
either the Pro circuit, Dep Pipes, fmf fatty, fmf factory fatty, fmf sst
pro circuit makes pretty good pipes. But I do agree with the guys below save your money for gas or something there is very little difference between the stock pipe and an aftermarket.
The guys posting are right... The factories have endless amounts of money to throw into R&D and the stock pipe is very good for the masses. If it isn't broke I would not fix it at this point... Practicing and riding every day will by far make you a better rider than bolting on any type of performance part. Now that said I will tell you that we did modify the motor on one of our test bikes in 2001. We had a YZ 125 (that had a 134 kit by US Chrome) FMF SST pipe, shorty silencer, and boyesen Rad valve. The reason we went with the SST is with the 2mm over bore on the cylinder, you also have to remove 2mm on the power valves. We noticed that the bike had lost some of its bottom and midrange grunt. The SST did help gain back the pull that was lost and that bike flat out hauled A$$...
Every person but you answered the original question.
Too bad you don't own the site, then you could delete all the posts that piss you off and have nothing but your lack of advice for people to read. That'll help them get a clue 'eh?