Yes I have a complete BLINKER FLUID upgrade kit that will make your blinkers brighter than ever, and if you act now I'll throw in a chrome muffler bearing at no additional cost. I'm messing, there are alot of things that you can do to the northstar engine, what are you looking for ie more horsepower, better gas mileage, ect ect.
Free mods? Not really. The car is so well designed that there's really nothing that you can do for free that will make any REAL difference in the car's performance. Of course if you want to talk "cheap" mods, then there's a few I can think of.
Intake and exhaust is the easiest things to mod and they can net some substantial performance gains as well as make the car sound sweet as hell.