I have Revo on my S3 (8P), and there is a long story to this.
Initially when I bought my car it was a pre-order and I couldn't test the S3 as none were available to test.
When I finally got to test one at a dealers I was gutted about how slow it felt. Part of this was because the car is such a civilised animal (its actually not slow at all - there is just so little drama). Also the dealer was running the car on 95RON which is never the best policy. Initially I wanted to cancel the order and go and buy something else, but it was too advanced so I couldn't without taking a significant hit.
I was running a Leon Cupra R with Revo Stage 2 pack (Full Milltek with race cats, Forge FMIC and 007P DV, Dynatwist, uprated mounts, silicone hose kit), and my immediate thought was to get Revo put onto the S3 in order to salvage the best from the situation. My dealer however said that they knew Glasgow Audi used MTM maps, so would rather I go the MTM route if I was going to remap.
At 198 miles I did exactly this, and paid up the money for an MTM map. I waited for the car to adapt and run in a bit, and at around 750 miles I was left scratching my head. The car didn't really feel that different.
In the end my frustrations built up and I went to see if Revo could help the situation. I had the car dyno'd and the figures with the MTM map were not what I was expecting. More than stock, but less than I had hoped for. I am not going down the road of quoting the actual figures becuase of the Dyno lottery scenario. Revo's map immediately showed significantly more power gains than the MTM map. The midrange surge improved significantly, and there was far more surge right to the end of the pedal. It has made the S3 into what I wanted, so I have had to find out the hard way. I am also running a Carbonia intake and panel filter with a Forge FSIT DV.
I've tested the car a couple of times at Bruntingthorpe (GTi International), and on a damp track with a boot full of camping stuff I got 0-60mph in 5.44s and standing 1/4 mile time of 14s. I then went to Audi Driver International at Castle Combe and the car held its own very well against more exotic machinery. On the day at Castle Combe I gave another S3 owner a demo in my car and he had previously owned a Mitsi Evo. He, like me had been slightly disappointed with the S3's OE power, but I can confirm our 3 mile run was enough to convince him that Revo was a good investment.
Onto the spark plug issue. I have suffered this. I live 0.9 miles from my place of work. The short journeys too and from work had meant my car was never seeing standard operating temps. I can't speak for the others on here, but a change of plugs has resolved the issue, and I am now not using it for the shourt journeys.
I know we could argue all day and night about suppliers of remaps. personally I think if you do your research, and you spend a responsible amount of money then you should end up with a fair product from an established dealer. My personal opinion of Revo is that of all the company's I have purchased maps from (AmD, Oettinger, Revo, MTM to date), they have always given me the best service and aftercare. They are very approachable and welcome customer feedback (and actually integrate the feedback into their product where appropriate). I had 2 Leon Cupra R's (one on a 53 plate, the other on an 05 plate), the first was AmD mapped, the second was Revo'd. The Revo car was a much more drivable car, and I could overtake with far more confidence. As apoint of note, on UK LCR's there was a issue with the stock map where the ECU could trip into safe mode when ambient air temps dropped below 4 degrees centigrade. Revo actually fixed this coding issue as part of their map. I spoke to AmD about it and got no joy at all.
I also rate the staged products Revo offer (Stage 1 / 2/ 3). I am pondering a stage 2 pack when it becomes available (with uprated fuel pump etc...), as if the Leon kit was anything to go by it will be a stormer. The packs always seem to be intelligently specced, well priced, an provide a great upgrade path for those looking to take their car to the next level.
People have mentioned the boost being high on Revo. With my select plus I can adjust the boost in steps from 1 through 9. I have never noticed the boost being excessive. During this cold spell I have been running boost 9 on occasions as the inlet temps are only running at 18 degrees centigrade so there doesn't seem to be excessive heat soak, and the car is not pulling back.
I can't comment on GIAC product as I have never owned it, and therefore don't feel in a position to pass judgment without qualified experience. I know the Volkwagen community seem to rate them quite highly so they must be pretty good.
I am a picky
b@$t@rd and a ****** demanding customer, and I can say I am very happy with this Revo product / package on the S3. This is my 3rd Revo'd car and I haven't had a bad one yet.
Do your research and take your pick, but make sure its on qualified experience rather than conjecture or hearsay!
cheers & best of luck
Warren