Simple answer Headers, Pacemaker comps. There has been dyno tests over & over again & these headers flog the rest except for JMM which cost an arm & a leg. The reason is they were developed for racing for the E series class & JMM developed their version as well. I am using Genies which are ok but don't compare, I got them very cheap. They are mandrel bend they also make a cheaper version non mandrel bend, wildcats. Don't waste your money like I did save for the Pacemaker Comps. As far as exhaust go, go for Redback or Lukey. Stay away from Lukey headers though non mandrel bend.

My understanding was that interferance designs like the genies were good for a boost over a wide rpm range...

Tuned length headers like Paceys were going to give you a bigger power spike in a narrow rpm range (the range that they are "tuned" for).

You might be interested: - I've got an Aerochamber on my car with all 2.5 inch pipework and 4480 Pacemakers. When I got the Aerochamber I already had the 4480's but the rest was a crap cobbled together mess - so I had a new decent quality 2.5 cat fitted along with what I think was a redback system - it had a hotdog after the cat, then went thru the Aerochamber and finally had a dogleg straight thru rear muffler - the note was very nice but the whole thing was as quiet as a std system! It was really funny because the exhaust place didn't want to fit the Aerochamber - they reckoned it was physically too big (in the end it fits fine) and they also reckoned it would be too loud - they talked me into having the dogleg rear muffler - but as I said: in fact it ended up too quiet!!

This is where the difficulty came in.... - I figured that if I had the dogleg muffler taken off the rear and a CHAMBER resonator or small straight thru chamber type muffler put on the front in place of the hotdog it'd be perfect (I've previously eliminated bark and drone completely successfully by doing that).

Unfortunately the place that fitted it all was happy to take off the rear dogleg muffler but were adamant they couldn't fit a chamber resonator or muffler up the front and instead just fitted a large hotdog - so the result has been that it sounds lovely and overall is perfect volume - but it's got that awful drone at about 2000rpm or so that's worse at part throttle than under heavy acceleration if you know what I mean (in fact it's louder at part throttle and 2000ish rpm than flat out at 5700rpm). I've left it be for the time being but will be trying some other exhaust places until I find one that will simply do what I'm F-ing asking for and fit a chamber resonator or muffler to the front.

What I set out to do: 4480 extractors, 2.5 cat, Aerochamber offset in, centre out muffler - EXPECTED result = good note, not too loud, no drone.

What I got: 4480 extractors, ceramic 2.5 inch cat, large hotdog, Aerochamber centre in, centre out muffler, rear dogleg straight thru muffler - result = lovely note, very quiet - pretty much stock volume.

So in short, the Aerochamber muffler gives a very nice note and volume BUT it needs a chamber resonator or chamber type muffler up front behind the cat to get rid of the dreaded drone.

Also, I could only get hold of a centre in, centre out Aerochamber (2.5 inch of course) - but an offset in, offset out or offset in, centre out would make installation much easier - and in fact, considering that the perforated pipe straight thru dogleg muffler REALLY quietened the system down and absolutely killed ANY drone - possibly an offset in, centre out Aerochamber might be an all-in-one solution and enable you to just run the single muffler with no need for a nything up front to control drone.