I think for redback on ebay they are around $550

Some mob on ebay flog a system that's single 3" rear section over the diff.

Manta make a twin 3", probably overkill though unless your going all out.

Twin 3" is good. I would have gone a 4" but car was pretty low and I wanted twin exit like the gt.

Im starting to look at upgrading my stock exhaust, but dont know which way to go about it?

High flow cat and replace the center muffler with a hot dog.

High flow cat and replace the center muffler with a hot dog.

im curious about this hotdog idea, I usually prefer a sausage roll.

what does this hotdog do exactly?

Ring Performance exhaust in Ringwood they do Twin 2 1/2 xforce for $499.

http://www.ebay.com.au/itm/Ford-Falcon-FPV-exhaust-XR8-sedan-XR6-Turbo-F6-/250984153549?pt=AU_Car_Parts_Accessories&hash=item3a6fd241cd#ht_500wt_949

Not bad for the price. Don't know what it is though.

High flow cat and replace the center muffler with a hot dog.

My thoughts exactly, should sound good, flows well enough and should be well under $500. IMO don't get a cat-back looking for performance if your cat converter is stock. Or figure out how much power you think you want, add 50kw and save and do it once aka Xforce/CES/Manta 3.5" single..

im curious about this hotdog idea, I usually prefer a sausage roll.

what does this hotdog do exactly?

Well you remove the center muffler for more noise but this can create a loud drone and some times sounds like a tractor at certain RPM, a hot dog muffler/resonator fixes the resonance in the system and should sound better then just straight pipes.