Well the K & N route is probably all you can do on the cheap. K & N has both the drop in filter and their CAI setup. The drop in filter is around $50 and I believe the full CAI is around $275. The full CAI supposedly gains 13 HP peak and generally 5 - 10 throughtout the whole RPM range. Of course this is information from K & N so make of it what you like. It does make the engine sound meaner though, but there are some quirks that go along with the system that may need to be addressed periodically as with any mod.
The LS-4 engine is pretty much a one off of the LSx engine line, so there are not many upgrades like you may find for a LS-1. Plus the transmounted engine makes serious things a bit difficult to work on without dropping the it out of the chassis. But FWIW, you do have the LS-6 heads so there isn't much improvement in that area that you may need to explore.
I hear there are tuning devices that can be used at least in the 2006 models. The 2007 models have a more secure system so cracking the codes and modifying the computer hasn't been done successfully yet by the manufacturers of these tuners, as far as I can surmise.
Some people have flipped their motor mounts or installed aftermarket ones and have seen a real SOTP improvement over the stock configuration. I guess the theory is the new or flipped mounts are stiffer, so more energy is sent to the wheels as opposed to the chassis. This is an easy thing to do, but you may run into strange vibrations and some uneasy feelings when going over bumps or stopping quickly. This may be worth a try, but beware.
Outside of that, your next step would be some nitrous oxide. There are kits for the LS-4 out there. A turbo kit is also available for around $6,000...But going with power adders, you may want to have an additional $2500 lying around to fix the transmission when it blows. Plus with the FWD set up, putting all the power to the ground will be difficult. If you put slicks on to maximize traction for these mods, you stand a real chance of breaking the half shafts.
The best thing you can do is run premium fuel through it if you aren't already. You probably will see a .3 to .5 second improvement in your track numbers. I did.
As for modifying the hood for a scoop, to each his own
. Personally I like the stealthy look of my car as is.
Bottom line, I bought my SS for the 4 doors and trunk with a sensible car in mind. What I got was all that, and some serious factory power in a sleeper form. In stock form these cars are about as good as you can get, so just enjoy the looks on the faces of your friends and others when you light it up!
Enjoy your car, and thank your parents!
