I've generally put them immediately post-turbo. True that the turbo soaks up some heat but I suspect that what you really need to know is the temo at cruise and the temp under a big load (going up hill, running a mile at WOR (Wide Open Rack) like on a race track). It's the heat increase that's worrisome to me. I like to keep the Cummins below 12-1300 *F.

Dan