^ back pressure is ALWAYS bad. its flow velocity people lose when running aftermarket exhausts.. that said, the muffler bypass pipes dont reduce piping diameter, they just shorten its length. i'd be surprised if the mufflers / by pass pipes did anything at all. the only horsepower to be gained on these cars via exhaust, would be to replace the cats with an xpipe

 

Well, I just got a GIAC from AWE tuning in PA. BTW, great service. I was in and out pretty quick and Mike was very courteous. Thanks AWE.
I drove home 25 miles half city half highway. Giac claims 15-20 crank horses but it's really hard to tell if it's that much. If I started out with 100 horses, it'd be more noticeable. Starting with over 300, it's hard to tell with the butt dyno.
The biggest thing noticeable was the responsiveness. Being a tip, I've always had the 3-4k range lag. Totally disappeared. The RPMs rev all the way up to redline quicker than before also.
Compared to stock, money well spent. I daily to work 130miles, so I'll have a better review in a few days.

 

This is really interesting but I wonder...

I was going to go with the K&N intake once I got my car back from getting my new engine. But I was also thinking GIAC was on my list of good cost/power upgrades (99 C2). Now I wonder it sounds like it would be a waste to do both... I think GIAC would be better if I only was able to do one (had AWE do my 1998 A4 1.8TQM) but I really wanted the sound that comes with the intake.

Does anyone have any proof that running both is detrimental?

Anyway just wondering, can't do anything till I get my car back and it is taking the dealer forever just to get the new engine none the less put in the IMS upgrade and install it.

 

Oh yea a comparison...

GIAC software

Overview
The finest chip available.
+ 23 hp @ 6000rpm for 1999-99.5 3.4l
+ 8~12hp for 2000-01 3.4l
7500 rpm rev limiter increase
Flashloader Now Available


and K&N
23hp @ 5500RPM

Also the K&N is significantly cheaper

Weird I just noticed the claim the same gains?
Anyway thoughts?

 

I ran both on my 99 C2 and didn't like what the K&N did to my power curve so I took it out and my car ran better with a simple K&N panel filter... I don't think they developed that tune for the 99 with an external filter...

the tune alone from GIAC is worth it... you'll feel a bit more beyond 4500 all the way to redline and it will eliminate any weak spots between 3-4000 rpm.... its a subtle upgrade.. its not going to decrease your 0-60 time or 1/4 miles time... maybe by .1 seconds... remember its only 20 hp but I thought it was worth it as it changed the power curve of my motor.