420a owners think hahn is great..4g63s think hahn's site is full of shit. a stage2 isn't even that fast..it's like mid 14..stage1 is like mid 15.. stage1 deff couldn't compete with stock gst/gsx and if it could..put a $50 boost controller on the gst/gsx and it'll creme the stage 1.. you need at least a stage2 to compete with stock gst/gsx..even then it's decent but nothing remarkable. My car is mid-low 14s and i consider it slow as shit..i barely have any mods. 14s are slow imo..13s are pretty decent..12 and under is fast..that's just what i consider.. but 420a turbos are very nice and i admire people who go the extra length to turbo their car, however i seriously doubt a stage 1 will touch a gst/gsx unless the guy is driving and automatic and has like big wheels and a system in the back and he weighs like 300 pounds and doesnt know how to launch with an automatic..imo get a stage 2 at least..stage 3 and 4 are really nice. if you're gonna drop 1 or 2 grand into your car for a turbo kit..might as well put a little more and get a better kit..cause if you put a stage 1 in your car and cant run with gst/gsx..why bother? get stage 2 and you probably/might beat a gst/gsx..it's like a 6 cylinder versus 8 cylinder mustang..if you buy a 6 cylinder and buy an expensiver supercharger..those only make them equal to mustang GT..why not just sell the 6 cylinder and take the money and the money for the supercharger and buy a GT instead of going through all that trouble to make it the same speed as a stock car..imo that would be stupid to supercharge a 6 cylinder mustang to make it equal to a GT when you could just use the money and combine it to buy a GT.