heres my question. i have a 4.6 gt. now i was going to trade it in for an 03 cobra. i wonder if it was possible to put 4v heads on the gt short block. my goal is to have 500-550 rwhp. what else would you have to change? im assuming forged internals, tranny, anything else? i mean if this process will cost a lot i might as well just get the cobra.