i have a really worked a15 and i have from the extractors back 2.5'' the a hot dog just before diff then 2'' from hot dog to straight through muffler and then chrome tip and it sounds awesome.

A hot dog is used for noise more than anything, my advice is get a good set of 'tuned' extractors(headers), something like genie or pacemaker extractors(headers) and go with an exhaust system that isn't to restrictive, one should be enough. Are you thinking about racing? or just a daily driver?

Got any pictures of your beast?

Thanks dd. I'd tried searching the forum but couldn't find anything! I gotta get used to the separate wiki pages...

I was planning on using a performance muffler, but wasn't sure if one muffler will be enough. I don't want it too loud or raspy, but it really needs to breathe with the cam and injection.

For a 6000 rpm engine:
A15: 2"
A12: 1.75"

Sizing for Performance

If you will be making over 100 HP (unlikely without head porting work), go with a larger pipe.

A hotdog muffler won't make any more power than other types of performance mufflers ... but are usually loud. Depends on what you like.

I'm planning on building a new exhaust, and was hoping to get some advice on what works with an A12/A15 engine.
I have an A12, bored out, with A15 head (approx 5mm planed off head/block), cam, double valvesprings, and Hilborn injection.
I have some Coby headers, and was thinking of using 2" pipe, with a single muffler. Would this be too loud or raspy, or have too much drone? Would I need a "hotdog" style muffler too?
Cheers