Dynos are tuning tools, not a tool to measure power, every single dyno run will be different. Ambient weather such as temp, humidity, elevation all say as to what the number will be as well. Not to mention that the dyno can be manipulated to read higher or lower as well.
Dont get me wrong, Im not complaining. I'm a fabricator, and this car came in for a turbo system that we are using for out future kits. I just took the car to the same dyno I use all the time. I dont care what the number is, I use it for comparison. This was the base line. I did take the car back a day or two later to verify the results. With another 4-or 5 pulls, all were in the 294 to 302 hp area. Yes it peaked at 302 with 2 degrees of timing pulled via hp tuners.
Every car we put on this mustang dyno is "low" compared to every dyno jet the owners compare too. One of the last ones, was a scoggin dickey motor that was sold as a 545 hp 6.0......well it spun to 300 even....through a 4l80e.......
FWIW i've tuned 20+ LS1 cars on this same dyno. This is my stock 98 A4 12 bolt rear tuned, then with a lid/filter installed and retuned, all done on the same day with minimal time between changes. All pulls started from same coolant temp.
Almost all bolt on 99+ cars I've done on this dyno make 290-320rwhp. Pulls are super repeatable with the error being +-1HP between pulls which makes seeing tuning changes super easy. Nothing beats a dyno like this for tuning. I think I ran a 14.4 at the track in it.
The l99 cars are turds from the factory. It sucks gm did this to all the guys want a auto tranny. My 05 a4 gto smacks around the a6 camaros at the track. My 13.0 to their 13.8 - 14.2. My gto was a turd as well and all I did was get a dyno tune. It really wakes up the car. The best advice I can tell you l99 guys is to get a dyno tune asap. In stock form the torque management will stop you from running a decent time. Its not the car at all.
__________________ 05 gto A4, sap grilles and front bumper
dynot tune, k&n cai, dynomax mufflers and dr's
12.80 @ 109.21