it depends on what sort of new muffler being put inmurcod wrote:I'd recommend fitting extractors and leaving the rest of the system standard (providing there's nothing wrong with it?)
I ran mine like this and had a huge improvement in low rev torque with my Hurricane 4-2-1 extractors. I then got the cat back done in 2" pipe with a new muffler etc and lost a lot of the torque. Power at higher revs was improved, but who drives up in those revs all the time????
some high-flow muffers are for sport car and they weaken low-end torque for high rev power
a so-called s-shape back pressure type claims to improve low-end torque for regular street use, I put it on and it works better than the stock muffler (well, it got a rusty hole)
ref: http://hk.f1.page.auctions.yahoo.com/hk ... 1111354675