[BiturboS4] Chips for free-flow exhausts

[Edwards, Dave]

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Carter,

I write from a fortunate position in that I have a custom design remap. As
I'm sure you understand, every engine is different, so to really get the
best performance out of an engine a custom map is the only way to go.

However if you don't have this option (but surely there are tuners in the US
who do custom maps?) then you have no choice but to get an 'off-the-shelf'
mapped chip. Clearly then you need to get one which was developed on an
engine which is as similar to yours as possible.
When I did my first mods, I was unsure whether or not to get the cat-back as
I was on a tight budget and needed to justify every cost (and those Porsche
brakes are damn expensive!). My tuner told me that I could add it later and
the ECU would be able to compensate for it. This should be true for all
chipped ECUs including yours. This is why I wrote that just the cat-back
should not be a problem.

Personally I don't believe that a chip which was developed on a car which
had the Miltek cat-back would necessarily be any better for you than one
which had been developed on a stock exhaust car. There can be enough
difference between two given engines anyway that having the cat-back is
insufficient to make a unique difference.

However, as I wrote, the full Miltek system is a different matter. I have
communicated with several S4 owners who have had problems with it on cars
with 'off-the-shelf' chips. Having seen the difference (on the dyno) that my
custom remap made after having the cats fitted on my car, I am in absolutely
no doubt that for a full Miltek exhaust, you need to have a chip which is
designed for this. As you have written, most of the serious tuners offer two
chips, one for the stock system and one for a free-flow exhaust system.

Cheers,

Dave

-----Original Message-----
From: California Fields [mailto:cfields72 at hotmail.com]
Sent: 26 October 2002 21:04
To: Dave_Edwards at iOra.com
Subject: Re: [BiturboS4] RE: Hesitation



Hi Dave. Thanks for your input. In regards to your point about a modified
ECU being remapped and probably not in synch with the exhaust, would it be
better to purchase a chip that was made for the exhaust setup?  I have the
GIAC X-chip and the Milltek 3" cat-back. I know that Stratmosphere has the
O.CT chip now and they say it was developed specifically for the Milltek
exhaust setup.  I wonder if the Abt is similar.  But, as you pointed out, is
this only true if you do the full downpipes and all?

Thanks, Carter.