I got pacemakers fitted to my AU a few months back,
$300 for the pacemaker extractors (go on ebay the same guy sells them for $260-280)
$300 for a hi-flow 2 1/2" cat
$300 for a off the shelf 2 1/2" cat back mandrel bend system
The sound from it is FANTSTIC, no drones. I've had heaps of people say how nice its sounds, people at work, freinds, guys down at the tyre joint, even commodoor people.
There is a slight loss of tourque blow 3000rpm but afterwards it go's like a rocket.
Next mod is 3.45 diff gears to help with off the line mumbo.
Oh, and i got the exhaust fitted at a midas outlet and I watched them do it, must say its the most pro job i have ever seen, took the poor guy 4 hours, remove old exhaust, fit extractors, bolt up cat, tack weld cat, take off again, weld it properly all the way around repeat process about 4 times for all the flanges in the system. very pro, very happy with it.
Be carful of people who will try to weld around the pipes when it is fitted to the car up on a hoist, never a good job.