i had 5" straight pipe installed and guy with an 2011 3500 dodge told me straight pipe does not allow any back pressure on turbo and it free spins unoiled when i turn it off. does anyone have any knowledge on this matter

A good turbo free spins when you turn the truck off anyway:cookoo:

Ive been running a full exhaust no muffler/ resonator for many yrs with no ill effects. I think back pressure would be a bad thing for the simple fact of higher egt's :shrug

Straight pipe 3" with no issues. I don't see the need to even upgrade my 2002 to 4". My EGT's are very controllable even towing up steep grades.

Tell him to pound sand, hes doesn't know what he is talking about.HMMMMMM yeah back pressure on an engine that is shut down, lets stop and think about that.....................

My system with straight through 4inch "muffler" might as well have been straight pipe. The only problem was noise towing... sounded great running empty but that's not why I bought the truck! Yes tubos free spin after shut down... if you idle the truck & let it cool off before shut down, it should minimize the turbo spin after.

As everyone else has stated, that's one of the dumbest things I've heard in awhile! :)There's no back pressure, because there's no 'front pressure'.. It's just spinning.. It's spinning no more or less than before the straight pipe installation, it's just probably a lot more noticeable (read: audible) now that there's no muffler to 'muffle' the sound.That guy doesn't deserve to drive a 2011 Dodge. He needs a Yugo.

I am running a 5 inch turbo back pipe and have had no problems for several years. Yes the turbo spins down at shut down but not for much more than a few seconds. I always idle the engine until the EGT is below 300 before shutting the engine down. The turbo will be a LOT happier that way.

Other than a 3rd gen with a stock manifold/turbo sounding like a wet goose fart, you won't hurt a thing. The turbo does the same thing with or without a muffler.My turbo spins for 20+ seconds after shutdown