GIAC Flash Review on the 991TT
 

I've been holding off on my review, though I've had the flash on my car for the past couple of weeks, in order to get more seat time as well as my driver side header gasket replaced (related to dealer not reinstalling exhaust properly after having the car in to fix boost leak). I had the car flashed at Rennology, had a great experience there, good guys, knowledgeable and friendly. I have been running the car on the 93 Octane program, but I plan on trying out the 100 Octane on the track this Monday.

In short, it's essentially everything Vic has said, the tune is great. I've had a lot of tuned turbo cars (and a GIAC tuned 997 GT2) and this is the smoothest and most OEM like program I've experienced, dare I say it SMOOTHER than stock. The throttle response is better, but by no means jarring, and the boost builds more quickly but smoothly in all modes, normal through sport+. I hate repeating myself, but the best adjectives I have to describe it are smooth and powerful.

I have about 1k miles on the tune, and no negatives to speak of, though my mileage may be slightly worse probably due to a bit more aggression on the throttle. :) It appears to pair very well w/ the Fabspeed full exhaust.

I will post some impressions next week after I run the 100 octane program on track, though I will do at least a couple sessions on 93 to compare my times and speeds w/ stock. :cool:

-A

Had mine about two months and I would same the same thing. It performs perfectly around town, and as well, at the track. The only downside may be the mileage issue, especially when combined with probably just about any exhaust. But if it is mileage you are worried about, you probably wouldn't be on this forum anyhow.....

Have you tried the 100 octane on the track? Impressions?

Has ANYONE tried 100 octane program yet? i just installed the 100 program today and am at 1/4 tank when the car drains down more the 100 octane is going in....what are the gains to the wheels supposed to be?

Well, based on the dynos on their web site, the non S gains 55/50 hp/tq on 91 octane and 105/65 on 100 octane. The delta is probably a bit less w/ the 93 octane program to the race program.

Is the over boost still functional? What happens if we need to update the software for other causes eg steering...will it affect the flash?
Is the gains more after a certain speed?
Thanks

well, all i can say is by the seat of the pants o-meter- the 100 race octane program is giddy up!! seems power comes on stronger and faster....like a boost of adrenaline...very nice...

seems to me that the difference between 93 and 100 is greater than the 91 to 93, but that makes sense...

if i wanted to run 100 octane in my car the whole time and leave it in race mode is the car safe and is that an ok thing to do?

What were your stock times/speeds and at what track? Thanks.

Going to get a GIAC tune myself.

Good question, hopefully Austin from GIAC pipes in here.

Autobahn in Joliet, IL, full track I ran 2:46 on the stock program w/ the Fabspeed last month, which was 8 seconds faster than last year w/ the 991S. It's a pretty technical momentum track, so the power of the TT over the S was probably only worth 1/3 to 1/2 of the gains compared w/ the RWS/PDCC/AWD gains. Max speed w/ the TT was 126 (12 faster than the S). I'll post up my times Monday after I run the 93 oct and 100 oct programs, as well as the max speed delta on the straights. I'm doing Road America next month so that will be a better track to assess the power improvements.

Funny, I thought you were talking about the dragstrip. Still, let's see how much time you shave. Good luck.

Thanks for the great review Jag!! Glad you're enjoying the new power. :)

The "smooth, powerful" sentiment is one I'm hearing a lot from customers who are getting the flash. I was the beta tester/driver of our Turbo S during the software development (it's a tough job I know, but someone's gotta do it! ;)), and I can tell you that this car is VERY deceptive. The acceleration, the shifting, the throttle input...it's all so perfectly balanced and smooth that after the flash, you sometimes don't realize how quickly your accelerating until you look at the speedo.

When we approach a project like this (we being GIAC and Champion), we're never done with development until we can say "yes" to the question...."Is this what it would feel like and drive like if Porsche did it from the factory?" The 991 Turbo software is a perfect example of that.

Yes, the overboost is still functional. Overboost is a built in function to control exhaust gas temperatures except in situations where you really want to get into it. We see value in retaining and are able to properly calibrate with it (some tuners struggle with this), so we don't see a reason to remove it on normal cars.

If you need a software update, you can always return the vehicle to stock prior to bringing it in for service, then flash it back later. If there are new revisions for the DME, we typically get them and update our software options with them. This means there is no reason for you to go into the dealer and have your software updated since we will be overwriting that with our software again anyways.

In terms of powerband shift, this software increases power literally everywhere. That said, we do retain safeties, so that the DME is able to reduce power at high speeds if exhaust gas temperatures are too high (this would be more prevalent with stock exhaust and possible stock intercooler equipped vehicles).

@AJag Thank you for the review and kind words! We're proud to hear how happy you (and the others in this thread) are with their Turbos. Can't wait to hear about race mode. hilarious

Thanks for the info above Austin!

Well, I had one awesome session on the track Monday before having that old boost leak problem rear its head again on the first lap of my second session. It was at the dealer a week and a half last month before they figured out it was the intake (last time I was at the track it was stock except exhaust).

I only did the 93 tune the one good session I had, and it was so much faster than stock it was glaringly apparent. Of course my harrys laptimer didn't work, but per my speedo I was hitting a good 5-6MPH faster on the straights, and wasn't even pushing it that hard yet. Given that and my butt dyno, I'd guess I'm making at least 70-80HP more than stock w/ the GIAC and Fabspeed combo. I was starting to feel limited by the tires (running Pzeroes) at that point, so I wasn't even planning on doing 100 octane if I would have been able to later.

Taking it to Rennology Friday to smoke test it, as my dealer obviously can't handle a boost leak. Any suggestions for what I should do so this doesn't happen again would be much appreciated!

Bummer about the leak. Glad to hear you at least got to have some fun with it though.