[richtazz]

your GTP has the 3.4 DOHC motor in it, and it's a fragile piece. I'm afraid that any mods that you try to perform will shorten it's already questionable longevity. As far as putting in a different engine, your 3.4 has more horses than the 4.5 and 4.9 caddy engines you mentioned, and they are too wide to fit in your engine compartment. Simple things like a K&N filter and freeing up the exhaust are about your only feasable options.