I'm definitely not doubting that. I am running the Hahn kit at 6 lbs...had a surprising run (65mph-120mph) against someone that had a 9lb setup with port fueler set up on his Hahn kit... and I was able to pull away from him. I am seeing some odd rumors that the new kit from Hahn with portfueler and AEM piggy back is only dynoing around 270-280 HP. Not sure how true that is...but I don't think I should have been able to pull away from the other sling especially with the extra weight of a passenger in my slingshot.
Oh, Sorry, I didn't mean to suggest you were doubting anything, I was just responding to the 6 vs 9# springs and the proverbial Turbo vs SC reliability. I will say this, Turbos are really susceptible to changes in airflow (in or out). I know diddly squat about the Hahn setup, but for example, as in my case, something as simple as swapping out the exhaust from Alpha Side exhaust to the Welter Stealth made a considerable difference in how the turbo spools up therefore I have a completely different feeling powerband that I had to get used to again.