[HiFlow5 0]

Sure you can plug the holes while the heads are on the car. You might have to remove a few other things though. You will need a 5/8" thread, 1" long bolt or plug. I used plugs that needed an allen wrench to install, from the hardware store. Its cleaner then a regular bolt and cheaper then going to a dealer for the plugs. Are you running an off road h-pipe? Cause if your not, removal of the smog pump and system will clog the cats from the lack of air flow the smog pump generates.

I did what your talking about doing this past summer. Heres a pic and you can see that it cleans up the engine bay a little bit.