Aftermarket diffuser exit exhaust dimensions?

[CosmosMpower]

Anyone happen to know some dimensions for popular lightweight aftermarket diffuser catback exhausts? Something like Stage 2, quicksilver etc. I'm looking to fab up a lightweight straight through exhaust with some bent piping and a generic magnaflow for temporary short term use.

[CosmosMpower]

I'm especially curious about the diameter of the piping needed from the cat into the muffler. Not sure if it's 2", 2.25" or 2.5" on this car.

[CosmosMpower]

Found the inlet pipe to be 2.5" Now I need to know the size of the actual muffler tank i.e. 2bular offers a 5, 6, 8" version. Would a 9" oval can fit inside the space?

[wildwhl]

A 4"x9" oval will fit...round is simply easier.

WW

[321freeflow]

Originally Posted by wildwhl

A 4"x9" oval will fit...round is simply easier.

WW

A round silencer is more efficient at silencing - important over here in noise-restricted UK.
I wouldn't go with 2.5" bore if I were you - just because the Cat Pipe is 2.5", doesn't make it correct.
2.5" means DRONE.
What you gonna use for silencer packing?

[CosmosMpower]

I don't really care about drone or even overall volume as long as it's not something ridiculous like 150+ db, it's going to be on the car only temporarily and not on the highway. I just want the lightest setup possible and if it makes any extra power that's fine with me too. I plan on buying a generic 4X9" oval 11" body length Magnaflow. I'm not sure why a round muffler would better reduce sound though. A 4" diameter 11" long round muffler only theoretically has 176 cubic inches whereas a 4X9" oval that's 11" long has more than double that.

Besides sound, are there any performance downsides to a 2.5 inlet and outlet such as killing too much backpressure etc? I thought the stock and stage 2 both used 2.5 inlet and outlet.