I have a 2002 Z28 6speed, I put on a magnaflow muffler, Z06 massair from SLP, Air lid with a K&N filter, And the air induction box that sits in behind the front grill.
I think stock 305 and with the mods 330-350 Rearwheel?????

 

No, there is no way you are going to gain that much from those mods. Maybe 315. Maybe. It depends, some people dyno 315 stock. Most don't.

If you wanted 350RWHP you will need headers and a whole new exhaust system, although it may take a bit more than that. Remember 350RWHP is over 410 at the flywheel. Do the math...you need to gain 60BHP from stock to get there.