I realize this is an older post, but felt I should add my
wood4heat, I have to disagree with you on the performance gain of the 4" diamond eye exhaust. I have it on my 02 supercab 4x4 and after reading your post I can only say I'm glad I had a tuner before I got the exhaust! with stock size exhaust(cat and muffler removed prior to new exhaust) and EDGE CTS on #3 I had to constantly watch the egt's anytime I had any kind of long hills with an 800 pound ATV in the bed;1400 was typical climbing a certain hill on the way home from riding,sometimes requiring that i shift down from 6th gear to keep EGT under control . after putting the 4" diamond eye open kit on it I rarely get over 1200 degrees and don't even have to think about downshifting to control EGT. The 6637 air filter kit also made a much more noticeable difference after the exhaust swap.
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2002 F250 super cab SUPER DUTY. 7.3,6speed! South Bend clutch,edge evo CTS, 35"pro comp on 17 MT wheels. 4"diamond eye exhaust.PRO-COMP6.5" front 5"rear lift.4.30 gears and shimmed trac-loc at both ends.custom bulged fiberglass fenders and bedsides with 3" rise by Perry's Fab N Fiber(thanks Mike). wrecked and rolled, but rebuilt both times by myself and and few friends.