do 99 GT heads work good on the thunderbird? does everything bolt up right like the intake and all that crap cause i have to have my head taken off to send them to a machine shop to get re surfaced....i need sugestion fast!!!! they are gonna start it on monday. please help me yall!!! i just need to know if they will work in place of JBL headers and still get some hp increase and sound increase. it they have them out why not do it now??