My 91 GT has stock headers an off road H and flowmaster catback and I really like the sound of it but I was thinking of going with an X pipe. Im sure there are a lot of threads on here about it but i didnt see much. Is there a real difference in power or sound. I also was wondering if anyone could help me with headers my last 5.0 had mac shorties on it and i like them but was wondering if equal length would be a better choice. Thanks for any help.