Well here goes , I just purchased a 97 f-250 psd e40d,4.10 rear, it came with a fipk (K&N) ,superchips 1705 programer. Gave 4000.00 for it ONE catch it had a dead hole ...., Nothing big just a dead #2 injector bought 8 ab code injectors for 100.00 replaced it and it runs real good. The truck has 280k Question is what is the difference between the two (AA&AB) Just put the 3'' dp and negated the cat I think it ran better with the cat and no muffler....What are some views on my purchase and the mods soo far and what else can I do? I also added an extra trans cooler in addition to the factory external. I have too put the pyro and the boost gauge in next Also I have a diablo trans valve I must put in as the 2to3 shift barks tires OUCH!!