Go with the 420a...at Stage II you will be in the high 13's with no internal engine mods. I would suggest a new clutch and a 3inch Cat-Back system. The Hahn Website has some information about the 420a and has been testing out their kits for years. Everyone wishes they had bought the turbo, but the Stage II kit will yeld 250-275 hp at the fly wheel...you'll lose some of that getting it to the ground, but you'll be faster than a STOCK GS-T. A GSX will still burn you off the line, they are so nice!

P.S. Stage II is $3049.00....Stage V will yeld 475 hp at the fly, but who has the money for that!

http://www.hahnracecraft.com/auto/eclipse/eclipse.htm
www.extrememotorsports.com
www.machv.com