New Garrett GT3788VA
The cat makes a huge difference in sound level and will actually help your turbo lag a bit. The small amount of restriction the cat provides maintains a pressure column in the exhaust post turbo. The pressure column makes it so that the exhaust energy is more readily available to act on the turbine wheel. I'm not talking about any significant amount of back pressure though, just a minute amount, and it will make a difference. This has been discussed years ago in this forum, with arguments both ways, but my 6.0 always ran better with the cat than without. My 7.3 doesn't care either way though.
Oh, as for the seat of the pants gain, if the truck had been running poorly from an ailing turbo, that's probably not too far of a stretch, but in reality, with stock programming, you're probably within 10-15hp of the stock turbo.
Sent by my right thumb!
The Current Truck (Oct-2013 to Present):
1999 (Early) F-350 Lariat, CCLB, SRW, Black/Tan
7.3L Powerstroke, 4R100, 4x4, 3.73, 37x13.50-18s, '05 Axle Swap, 6" Fabtech lift, GTP38 "D66" turbo upgrade, SCT 4-position chip with custom tuning by me, Straight Piped 4" down pipe through 5" dual stacks, N-Fab full length triple steps, Pro-Tech cab guard and tool box, louvered 5th wheel gate, Hella 500 Fog and Driving lamps, much more to come...
The one I'll miss, (Mar-2009 to Jan-2014):
2000 Excursion XLT 4x4
6.8L V-10, 4R100, 4.30, 285/75-18, 271whp / 388wtq
The one I won't, (Jul-2005 to Sep-2012):
2005 F-350 XLT, CCLB, SRW, 4x4 FX4
6.0L PSD, ZF-6S650, 3.73, 35x12.5-18, 4.5" Lift
Last edited by IdahoF350; 10-11-2014 at 06:36 AM.