BRD-PREY

iTrader: (5)

My thought is a 2" or even 1.5 inch exhaust cutout would be as effective as a full size 3" cutout. I figure that since its not an exhaust divertor that it only needs to aloow enough additional flow as to remove excess backpressure.
The original 3"-4" and muffler are still flowing so the cutout just needs to provide that extra flow above what they are capable.
This would make it much easier to fit under the car.

Please chime in if you see a flaw or agree with this conclusion.

Thanks
ed

RedRocketZ28

iTrader: (19)

My thought is the exhaust is going to take the least restrictive path it has. I know at idle most of my exhaust is going out of my cutout and at WOT I imagine a lot more is pushed through the opening.

BRD-PREY

iTrader: (5)

I agree it will take the least restrictive. So when the 2" cutout begins to reach it unrestricted flow capacity then instead of pressure(back) curve building up rapidly the full length exhaust system flow path is still available to provide the a path and back pressure will still be basically non-existent at the point of the cutout.
That is at least what I'm theorizing.

I was basically looking at cross section of available flow area. 2" cutout and 3" exhaust system. Thats perside. Thats a lot of flow area.

jimmyblue

iTrader: (11)

Pressure stackup is going to depend inversely on the
total cross section, mobetta. Whether it is -that-
much better, needs more facts and calcs than hand
waving.

BRD-PREY

iTrader: (5)

I'm not talking about performance figures. Like idea back pressure etc. I was just hypothesizing that your cutout doesn't really need to be the same size as your pipe because its not diverted but has both paths.
This would aid ground clearance alot.

BRD-PREY

iTrader: (5)

I talked to a design engineer with Borla and he seems to think it would be fine with a smaller cutout.