Which cars adds the most power from just a tune?

For an oddball engine: The GM LQ1(The 3.4L DOHC v6) in the Luminas etc) made 210 HP stock. The rumor has it that when GM was developing this engine it actually made 275HP and they de-tuned it to 210HP because the FWD transmissions they put it behind couldn't handle the power and torque the engine produced. I know the Fiero guys are fond of using this engine for their swaps and that they rev the thing north of 7k RPM. If that rumor is true...a 60HP gain from a real tune seems pretty impressive. I don't know if I beleive that 275 HP number...but there are dyno graphs out there that prove it was de-tuned at least 30HP...which is still a huge huge gain on a NA v6 with just a tune

In reply to Welly :

And that's APR, who are usually on the low end of the spectrum. 
 

For just tunes, the Audi engines gain a ton of power, however on potential, the VR6 is possibly the most insane engine VAG has made. It's not hard to make one mental, and their bellhousing is the same as the rest of the Audi engines.