Re: A4 cat-back exhaust recommendation

[Huw Powell <human@nh.ultranet.com>]

> I have >experimented with< this issue and here's my 0.02c FWIW:
>
> Reasons to modify standard exhaust are:
>
> 1-performance gain: on a normally aspirated car these are pretty small,
>   almost certainly less than 10hp and this is barely perceptible, unless
>   the stock system is *very* restricted.

I put what was essentially a 2-1/4" system from an old 5kt behind a set of 4kq
headers/downpipe on my 82 coupe.  The difference is quite palpable.  The sound
ain't bad but there's a bit of a "whirring" noise around 3200 rpm - maybe the
empty cat resonating?  the difference between the coupe and 4kq stock systems is
10 hp, which I have been led to believe is just due to the only difference, the
exhaust system.  Maybe I even got a couple more from the bigger pipe & no real cat
(a temporary situation...).  That's over 10% in this case, no wonder I can feel
it.

Sorry no dyno tests or time slips tho'

> 2-sound change: this gives the *perception* of greater performance. Louder
>   is not necessarily better - look for a system that improves the *quality*
>   of the sound.

Yeah, I'd prefer silent but deadly.  As it is it sounds a bit like a 5 liter
rustang when idling.  Just not when revving!

> 3-looks - this is purely dependent on the tailpipe design and finish and is
>   very much in the eye of the beholder.

yeah, well, mine's fairly ugly.  Muffler's a bit big for the car and the tailpipe
is a wierdly bent (per my foolish diagram) Mieneke job.  Works though, whole thing
cost about $350 including S/S hardware and chain type hangers.

> I don't believe the expense of a full cat-back changeover is worth it on a
> normally aspirated vehicle and you can achieve the sound/looks result with
> the far cheaper Remus or similar mod.

probably depends mostly on, as you said, how restricted the stock system is/was.
The stock 82 coupe has this pathetic little exhaust manifold that crams everything
into about 1 1.4" pipe.  The 4kq headers are way cool, gently guiding the gases
down to a roughly 2-1/4" outlet.  So I had a lot to gain.  Dunno about the A4...