chadlet

I was wondering if when you decreased back pressure in your exhaust sytem would that make you start running rich? I just installed the O/R H pipe. I emailed bama for a new tune because of the o2 sensors but he told me that he already does this in all of his tunes. How can one tune be good for both exhausts systems? Just trying to figure out why it feels so much slower since I changed the mid pipe. I understand that I reduced my back pressure by removing the cats but from what i have read that shouldnt matter as long as the engines tuned for this. Something about the valve overlap. I guess I should get it dyno tuned to be safe.

drbobvs

Logic would dictate, as well as some people claim, as you decrease your backpressure it would make you run leaner. However, our stock exhaust flows so wellI just haven't seen it occur on N/A cars. Removing your cats without F/I does not seem to effect the A./F all that much.

Brian_Zinchuk

drbobvs: whats your a/f usually at?

mygt500

His is at about 11.4 (at least that's what it says from his dyno thread)

ski

Ano/r h pipereduces low end torque due to the loss of back pressure, and that makes the car feelsluggish at lower rpm's. But if it'sslower across the entire rpm range, then something else is wrong.

drbobvs

Yes, my dyno yesterday showed a low of 11.1 and a peak of 11.6.