I have the S475 83/74 turbine on mine and it's responsive for sure but I have issues with the boost dropping off up top. I haven't had enough time to figure out if it's a wastegate/boost controller issue or turbine sizing. So I'm considering upsizing depending on what I find and dealing with more lag.

 

i doubt the s475/83 is dropping off, that turbo is plenty capable of making/holding power , what ar of exhaust housing do you have?

 

How much power are you making? Boost level that it's dropping off? RPM you're reving to?

 

I'm not sure on the current power level. It made 542 rwhp on 8 psi. I've been hitting it at 16 psi but the boost was falling down up top. Shift at 6250 eve though it's commanded at 4600. I don't rev higher for transmission longevity.

I made some adjustments to my boost controller to stabilize the boost but haven't had a chance to test it yet.

 

Seriously??? Why so much lag there?

And no more than 6250 for tranny longevity?

 

Dunno why it delays the shift but it seems directly related to power. On low boost there's less lag.

 

I have the same problem. Commanded at 5200 and it'll shift at 5800. The ECU thinks it's in 2nd after the command, but logs will show it 2nd gear at 5800 for a second before it shifts.

 

Looks like there is enough air there for a 6.0L with a single 475

Wondering if you have a boost leak. BOV, intercooler coupler, intake, etc....

 

how can a truck that never came with a turbo have lag?

 

Not going to sugar coat it, that doesn't sound too awesome :/ Who built the trans and/or installed the shift kit? Whats all in it?