... been told that the engine prefers to work off back pressure and that an exhaust system would hinder it more ...
back away from the idjit who told you this SLOWLY, lest .
Exhaust systems work off of SCAVENGING, gottdamnt.
... wondering what performance mods you can do to the 6.0L in an 09 suburban z71?
Was thinking of roller lifters and roller rockers but don't know how much of a difference that would be and if it's worth it.
Will take all suggestions for any performance mods.
Before you get into modding engine hardware ...
1. What axle(s) ratio do you have?
If you have a 6L80, you want 3.42 (mostly highway) or 3.73 (mostly stop'n'go, some towing),
or 4.10 if you tow very heavy very often.
If you have a 4L60E, you want 3.73 (mostly highway) or 4.10 (mostly stop'n'go, some towing),
or 4.30 if you tow very heavy very often.
Axle gears address how much power is being put to the ground.
Not cheap, but you can't beat the bang for the buck, plus the transmission will last longer.
You will only suffer worse MpG if you drive like a cabbie on meth.
2. don't know where you are, but go find a local tuner who will sit in your vehicle for an hour.
The ecm & tcm tune that will result will make you wonder why GM was holding back so hard.
Costs less than an axle, completely changes the vehicle's personality.
