exhaust backpressure??
#1
#3
in truth your truck isnt pushin so much fuel and air to make enough exhaust that a 5" would help you out. now if ur gunna build the truck up a lot then a 5" would help later on but the help it gives you later on would be so little that i dont really think it would matter. now im not an expert so dont just take my word for this, wait till someone smarter than me comes on and says im right or im wrong
#4
#5
#7
#8
im pretty sure the stock turbo has a small back pressure plate built in and even so not needed with the turbocharged engine itll be fine so yea ur choice between 4 or 5 my suggestion 5if ur planning on intake and chipping it just personal preferance to keeping egt's down
The back pressure valve is not to control back pressure like that, it is used to help put a load on the motor when cold and raise EGT's, oil and water temps...
There is no "point" where a 5" exhaust will gain you more HP... 4" turbo back is all you need, anything else is for show, or sound.
#10