upgrade

Hi, got a 1991 all stock conv GT and trying to keep it factory as much as possible but was wondering what would be simple upgrades to get a bit more HP or upgrade any things that would benefit the engine in 2011 technology that in 1991 wasn't that great. Oh, an by the way its a 5 speed as well...

Edit: Front seats are Gone! Rear seats are still available, see pictures below!! Hey guys, I recently got a great deal on Mach 1 seats and could not pass them up, which in turn leaves me to sell my stock seats. They're out of a 97 GT, with 60k miles. Overall in great shape, back seat has a small...