[89IROC&RS]

catalytic converter is for emissions, putting in a strait pipe will reduce backpressure for a few ponies, but call me a treehugger, i think the state of affairs with the environment dictates the use of a high flow converter, but its up to you.

For spark plugs i use AC Delco units, but Bosch is certainly a fine brand, so you could use those in the camaro just fine.

EGR is not for reburning fuel in the exhaust, this is a common mistake. What EGR does is to circulate inert gasses into the combustion chambers, this lowers combustion chamber temperatures, which lowers the chances of detonation, reduces emissions, and allows higher compression. Leaving it in a state of disrepair with cause your engine to run rough and get bad gas mileage.

running the 93 octane gas will not hurt your engine, but i dont think its nessesary, check your owners manual for what octain they suggest. octane rating is a measure of detonation resistance, a higher number equals a higher resistance to detonation, but the fuel tends to burn faster. so lower octane actually should in theory put more constant pressure on the piston and give you more average power. So most of the time, you would want to run the lowest octane you could and stay out of detonation.