A 99 SS only has 320 hp. A 99 Z-28 has 305. For 1500 bucks more, I'd go with the SS. It will hold some resale better and Im gonna guess you probably aren't going to go nuts on mods.

The 96 SS exhaust has the 2 tips on the left. Sucks. Sounds awesome stock though.

 

the two cars will perform the same. the 320hp is just another lure. all v8 ls1 fbodies are essentially a 350hp ls1.

 

350 horse? Where you gettin' that?

 

LS1's are rated at 350 hp. Go to any parts dealer and look into an ls1 crate engine. Same that's in the corvetes, camaros, trans ams, gtos.