I've been talking to a guy at banks, who told me they used to have a great y-pipe for the IDI fords, but they discontinued it and the only hope for performance with the banks name on it is a turbo. He even mailed me a booklet...
Xtremediesel.com has a cheap MBRP system for the powerstroke($289), but you'll have to adapt it to your factory y-pipe.
Dynomax sells a full kit. 2 1/2" down pipes into 3" back just before the straight through muffler, then 4" all the way back to a 5" stainless tip. Jegs has the best price i've found, $331.99 and since i'm about 40 min from Columbus Ohio, i can pick it up in one of there stores to save shipping.
As for an intake, all i've seen is some good little tricks to modify your factory intake a little, or Hypermax sells a cowl induction kit for there turbo systems that could be modified to fit for an NA motor. Don't forget the K&N.
1987 F250 XLT Lariat
Regular Cab 2x4 6.9L 5-Speed
Homemade Propane Injection.
RUNS ON PURE WASTE MOTOR OIL!
No more diesel for me...