As others have pointed out, simplest answer is turbo > supercharger.
The 3.4L DOHC V6 (LQ1) available in the first gen w-bodies made a max of 215hp stock, but regularly produce well over 300whp on just 6-8lbs of boost (not to mention the 60° V6 sounds infinitely better than the 90° motors). There's a reason Fiero guys love that motor. Here's one producing 417whp/427wtq on just 8.7psi.
https://www.youtube.com/watch?v=-6jv_s1hUJg
Another example is the 3.1L found in the gen I Ws. They were only 140hp n/a, but the McLaren Turbo version made 205hp with a TINY Garrett T25. That's a 65 hp gain from a turbo that's way too small for that engine (GM claimed it was to eliminate lag, but let's get real; they didn't want the TGP romping on the 'Vette). Compare this years later to the 3800 starting out with 195hp, but only gaining 45hp with a supercharger.