This past summer I jumped over the fence and purchased the Eurocharged pulley and tuning package combo and it has worked flawlessly
It was tuned on their Dyno-Dynamic and gains were between 20 and 24rwhp peak, but most importantly, I saw the same gains under the curve from 4,200 to 7,500. Below 4,000 rpms, gains were 12 and 17 rwhp. All this in the super hot Texas heat.
About three weeks ago I visited a buddy's shop who happens to own a Dynojet dyno, we were just sitting there eating some fast food and decided to strap her down. The dyno results were: 467 best and 461 worse SAE; according to the dyno reader, air temps were in the 80* and 82*F range. As a comparison, earlier this summer we dyno'd the car there, air temps then were around the 75*F range...so pretty similar air temps tuned vs. pre-tune. Results were between 438 and 443rwhp...these results were achieved with the CF removed, homemade air scoops and K&N drop ins. Bottom line, my tuning investment was a good one and it works!!!
BTW, at one point we decided to just keep pulling it; four times back to back never turning the ignition off and the car still responded with a 458 rwhp! The cool part is, A/F were in the 12.7 range in the lower RPM's and between 12.5 and 12.3 in the very high range (6K and 8K) which I asked for. Perhaps the car could have made another 3 to 5 rear wheel ponies with a slightly leaner A/F on top but who cares, I prefer safety and longity vs. having every ounce max output.
The car feels better on the road, the mpg has improved and heck, I leave it in P400 99% of the time because the car feels like its in a mini M-mode even in this setting. The car feels purely insane in P500 or 500s; it's really fun to drive now.
I highly recommend giving these guys a try; you will not be dissapointed!!!