Yep, what he said. Thing is, there's virtually no aftermarket for Crown Vics, either. Modifying these cars requires some ingenuity and imagination to adapt parts made for other cars to work.
If you want to talk to a bunch of people that really know the 4.6 cars inside and out, I'd suggest joining up at CrownVic.net
and asking them. Lot of knowledge over there. Good luck!
1989 Ford Crown Victoria Police Interceptor
2bbl Carbureted 351W V8, ported and polished E7TE heads, Edelbrock cam
AOD Transmission with B&M Shift Kit
3.55:1 Positraction Rear Axle
Visit My Car Domain Account Here