If you get the emissions-legal 165's, they can simply be bolted onto your stock engine. I'd want to replace the fasteners with ARP hardware - either new bolts or studs.
The AFR's will show a signficant gain even with the stock cam. Keep in mind when you start changing the cam (heart of the motor) you really need to think through the entire combo to optimize your results. There are lots of folks out there running aftermarket cams (and other parts) who make more power than stock, but also have an engine with very poor bottom end power - which doesn't make for a fun or efficient street car. So the place to start is knowing exactly how you intend to use the car and what you want out of your mods. Got to have that nailed down before you start picking parts.
Also, the 94/5 computers are MUCH more sensitive to changes than the 89-93's are, so the further from stock you go with your changes, the more likely it is you'll need to alter the ecu to get it to run well. Contrary to the other posters comments, AFR heads with a good intake and exhaust system and stock cam will TOTALLY wake up a stock-cammed motor and will not require any significant tuning for the ecu. The efi is mass-air -- it senses how much air is entering the engine and selects the appropriate amount of fuel to inject. So if the cam stays stock, you shouldn't require a chip or tuning other than timing changes. By the way, to capitalize on the AFR heads, I'd suggest an aftermarket intake (GT40, Cobra or Explorer will work well with the stock cam), and long tube headers with a free flowing exhaust system. Those changes will make a noticeable difference without negatively impacting drivability or fuel mileage if you can keep your foot out of it. Change the cam, and things get much more interesting in terms of drivability.
Good luck with it.
