is this possible?

[GrayZ]

8388 wrote:"I own two ZR-1's and you probably won't like what I have to say, but I would do only bolt ons. The LT-5 is a bit too complicated for internal mods, in my opinion. With the right bolt ons you can make 400+ to the rear wheels. My 93 makes 411 rwhp and the intake has never been off, and it does that without aftermarket headers too. In my opinion it's best to achieve the 500+ hp in a regular C4. It's cheaper, and easier to work on, and when it's time to sell, it's easier to sell a modded regular C4 over a ZR-1".

I posted on another forum i belong to. dometicmisfits.net
the above mentioned quote..was from a guy we call numbers guy,
he seems very knowlegable about cars...and owns quite a few it seems..but...when i posted the question to the forum there..about some upcoming mods..i have been thinking about...he anwsered with the above quote...my question is

Is this possible?? with just bolt on's? cause i have headers...and corsa exhaust..and i only have 353 rwhp...before the corsa.
when i dyno'd in may...i was wondering...whatcha think?