im at 570 right now on 38's with a very driveable set up. I run the 205's so im running a little warmer at the moment. I do run a NON VGT turbo, and i love it. I is slightly more laggy than factory, but i cam from a 64mm SSX power max that was a VGT turbo, and i think the truck is just about the same spool...i start building boost around 1800 rpm. I will tell you once this thing lights...im at about 48-49psi, and the truck runs quick.....i have no problem spinning my 38's. my s366 with the housing size is just right. I would get ride of it do go twin..which is what im working on. on the stock FICM
tune i was seeing egts
around town in the 800 range....at wide open i would be at 1700...once the turbo spools up im around 1200-1300 give or take. I would think this turbo with 190's would be a clean streetable set up. as wildrunner said...600hp on 38's is not easy....trust me i know!
As far as your transmission goes if you leave the thing stock, you going to blow it, its just a matter of time. Many people will say run it till it breaks then fix it...i toke a more proactive approach and just built the trans while the truck was down. i have the iron pac 3 from sun coast along with billet shafts, and a sun coast converter. The power gets to the ground.
For re gearing...its ideal when you step up to larger tires, but i opted to run the stock 3:73's, something about 80mph on the highway at around 1900 rmps...just feels right. i will be leaving the factory gearing for now.
MPG's....i havent run the truck with the new turbo long enough to get through a tank of fuel yet, but i will say on a 2 hour trip last summer on the old turbo set up...i was seeing 18-19mpgs....cruising 80-85. Around town right now my factory guages tell me im at 14.5, and i do not drive light on the pedal around town.
I do run the CTS monitor in the truck, however i also have 3 pillar guages...egt, trans, boost. I think the Cs or the CTS are well worth the money. But you have to use it expandable components with it to get the full use out of it.
For a preference on Turbo....even with the awesome results that wildrunner saw with that stage III turbo, im still more a fan of the NON. although the VGT is a fantastic street set up, i opted for the NON because it allows me to look into twins down the road (Apparently down the road was not as far as i thought) and also i love the power that i have when it spools...and the sound...while it doesnt add much power, it sounds awesome.....
there are many ways to get to 600hp...just make sure you build the engine to support it!