When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
A couple of weeks ago, I had my 00 C2 tuned using Viezu Mapping. The car is stock except for TopGear 200 CEL Cats and Fister D mufflers. Below are the before and after Dyno results.
I am very please with the outcome. Throttle is snappy. The car runs very smooth and pulls hard at about 4300 RPMs. Worth the $$
The baseline includes the exhaust mods. Most stock 996 have between the upper 240s to lower 250s rwhp. The increase is from the tune alone. The dyno shows the results. Not sure how the dyno shop would fudge the results...
There are many ways to fudge dyno results, one thing I always look for is the Standards they use for correction factors, the two used are STD and SAE, both are different atmospheric corrections, and come up with different H.P. and Torque. neither are listed on your dyno sheet.
Looks to me like the "tune" traded a lot of low end tractability for peak power at higher RPMs. That's OK if that is how you use the car, but I would think it would ber doggy in day to day traffic.
Actually...the power was improved throughout the complete band according to my 'butt' dyno. . I do not feel any flat spots (which I had before). Before the tune, the idle was not as smooth as I felt it should be. After the tune the idle is smoother.
At the end of the day...whether or not I actually got 24hp from the tune....the car feels stronger, idles smoothy, and doesn't have flat spots.
The car is not a daily driver and is not tracked, It sees spirited drives on the weekend.
The total cost was $750. This included the tune/program and dyno time. The ECU was flashed in a multi step process. See below:
1. shop got baseline dyno
2. flashed ECU with tune from Viezu
3. shop dyno the car again
4. sent dyno results to Viezu
5. Viezu adjusted tune and emailed file back to shop.
6. repeated steps 2-5 until tune was 'approved' by Viezu.
This was not a one and done flash. It was a custom tune adjusted by results on the dyno. This is why I went with Viezu because the tune is specific to my car and geographical location. Very pleased with the results.
Our dyno does not use SAE correction factors. That is what you would see on a dynojet. We use an atmospheric correction calculated by DynoDynamics which came out to around +3.5% on your day if I recall correctly. STD is usually a smoothing factor again used on DynoJet software. The pulls were done on the same day under extremely similar conditions without taking the car off the dyno or changing any calibrations. You would be hard pressed to find a better comparison scenario.
09-11-2017, 10:49 AM
Viezu Tuning
. I do not feel any flat spots (which I had before). Before the tune, the idle was not as smooth as I felt it should be. After the tune the idle is smoother. 
