[BiturboS4] mod feedback

California Fields cfields72 at hotmail.com
Wed Oct 23 14:45:47 EDT 2002

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Hey guys. I was hoping to get some feedback from you about the chip and
exhaust mods I've done recently.

I first installed a complete ECU with GIAC-X chip. The power gains are
enormous. Some things I noticed were:  turbo "whistle" escalates in pitch more
quickly and it comes on sooner when depressing the gas; engine response is
much more sensitive to INITIAL movements in the gas pedal...almost to the
point of being a little jerky...but is DELAYED in response to large movements
in the gas pedal (like a turbo lag or something).  It's kind of hard to
explain but does this sound normal?  Here's an example of the delayed
response:  I'm cruising along in 3rd gear at about 3k rpm...I abruptly press
the throttle down from about 10% (cruising) to half way and hold it....the car
lurches forward with strong force but then the power backs off a bit...kind of
like there was an initial spike of pressure but then it equilibrates to a
plateau of power (still accelerating strong but just not AS strong)...kind of
like I pulled back on the throttle when I really hadn't.  Is this a normal
turbo phenomena?  The S4 is my first turbo car. Also, if I start off the same
way (3k rpm cruising) and floor it, the power is enormous but it doesn't feel
as smooth as the stock was (little surges and recessions are felt as you go up
the powerband).  Is that normal?

Lastly, when I installed the Milltek 3" cat-back after the chip (which sounds
great - much quieter than I expected - hardly noticeable when cruising), the
abrupt power surges seemed to go away (i.e. it seemed a little more linear).
It almost feels like there is LESS power...but I'm thinking that's because
it's smoother (I hope).

Any feedback about this stuff?  Thanks.
Carter Fields, San Francisco
GIAC X chip
Miltek 3" cat-back
Stratmosphere short-shifter
AWE A-pillar boost gauge

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