since nobody has posted it yet - you don't need to drop the tank to remove the fuel pump. there's an access cover under the rear passenger-side seat. saves a LOT of effort, and the pump can be changed on the side of the road (i know, that's where i changed mine). i bought a japan-made pump at my local parts store for $78.50.
i'd put a stock exhaust on. everything fits, and it can be done for less than $500 for everything, including the cat and shipping. see my "maintenance thread" for details/info. the gains in "performance" by changing the exhaust only are minimal, so why add to potential problems?
http://www.toyota-4runner.org/classic-t4rs/155008-wallys-87-4runner-upkeep-thread.html