i just got a 2003 GT for my girlfriend and after owning many ford trucks i can say this car is the best and quickest ive ever driven. i got a few questions about some basic bolt ons. im thinking about adding some Flowmaster 40 series mufflers and keeping my stock piping and tips. is this adviseable? also thinking about adding the MAC intake and MAC long tubes for $350 its a deal. the Steeda lowering springs are priced nicely also. are these mods in my cars best interest?