3" benefits

qb6fire · April 9, 2015

Looking into a new exhaust simply for sound but was wondering if there is any benefit for going with a custom system with 3" pipe vs just a new muffler.

07Softail · April 10, 2015

There is benefit in large diameter tubing but too big will kill low end torque. 3" is about optimum for a single outlet exhaust being the stock pipe is 2 3/4". Larger pipe means more noise too.

RT

qb6fire · April 10, 2015

Thanks for the info.

Ended up staying on my budget and staying with stock pipe and putting on a magnaflow 14" with a turndown before the rear axle.

Evanski9 · April 10, 2015

I thought if you keep all 3 CAT's you should have enough back pressure. I did not lose any low end.

07Softail · April 12, 2015

I thought if you keep all 3 CAT's you should have enough back pressure. I did not lose any low end.

It has nothing to do with back pressure.... that term is a myth. It is all about exhaust waves and pulses. With a larger pipe say 4" or so on a gas burner you would lose low end torque big time. As I said 3" is about optimal on stock engines and the stock pipes are 2 3/4". If the pipe is too large hot gas will cool and slow down losing the scavenging effect therefore not power producing. FYI I am running on my 2014 RCSB Silverado 5.3 the kit for the 6.2 liter engine which is 3.5" with the 3rd cat delete and it feels (butt dyno) the same.... but If on a real dyno it probably shows a slight loss on the low end but future mods I have planned will benefit with the larger 3.5" system.

RT