Re: Factory exh systems Vs "'Trapps?

[glen.powell@smc.com]

1. How is it tuned?

Via removable baffles. No baffles is totally open, no restriction
whatsoever. The next step
in increasing backpressure is to attach all of the baffles, more baffles
equals lower
impedance. Then remove baffles to increase backpressure further 'till you
get the
balance of high-end and mid-range that suits the conditions at hand.

2. How does tuning affect engine performance?

Example: It's easy to hit the rev limiter in the '84 4000Q auto-x car with
the exhaust
open and much harder with 7-8 baffles in. This shows a big improvement in
top-end
power due to increased breathing ability. The engine really gets stuffy up
around
5500 RPM with 7-8 baffles on, but had great mid-range and low-end torque.

3. Will I loose much low-end grunt?

Not if you tune the 'Trapp for low-end/mid-range torque.

4. Is it obnoxious(loud, in comparison to stock & other perf. exhaust)?

Depends on your tates and perspective. I run my '73 RA IV 455HO Firebird
with 2x 2 1/2' pipes
into totally open 'Trapps, a totally straight system. It's louder'n hell
and sounds like a large
pack of Harleys roaring down the highway, but I *LIKE* it that way!      :)
Seriously though, with a turbo you can run the 'Trapps open without too
much noise.
The atmospheric cars, especially 4000Qs with their factory tubular headers,
are much
louder and you will likely want some baffles on there for street use and
torque.

5. Another big issue, cost?

'Trapss run from ~$80 to $160 US depending on SS Vs mild steel, size and
source.

I would plan to go 2 1/2" on the SS piping with no mid muffler and just the
'trapp at the end. Also does anyone know if I would be allowed to change
the exhaust manifold and downpipe to older version of the system(dual
outlet manifold-stock on older jettas) in the stock class?

Nope, can't change anything from the converter on forward, but that 2 1/2"
pipe into a
'Trapp sounds like the hot, legal setup.

-glen

TIA. The info is always from you guys(as opposed to r.a.vw.

Chad
shepherd.31@osu.edu
86 VW GTi
87 Audi 4KS
81 Audi 2-door 5+5