The PLog will definitely put through more air than your current PEM. You can only scrape out so much of the PEM till it becomes brittle and breaks. The PLog was designed from the inside/out to give you the max air flow in that design of Manifolds.
Like you, I thought about just doing the 3" DP and a PLog, but after much debate, I have decided to go the headers route. Cause sooner or later you are gonna get that itch to want to hit the low 13's or maybe even high 12's. I know some folks got those times on PEMs but that was with good tuning ontop of other modifications/track conditions etc.
For the price of a ceramic coated PLog, you are already at $200 bucks roughly. And for about $300 more you can get set of coated PS's from Wbody or ZZP. So I have been saving my pennys to at least get to that price range for the PS's maybe if the Bank Gods allow, some SLPs
As for your 72mm TB, I was kinda turned off to that, even though I had gotten my LS1 TB just recently, due to the fact others have said to really gain the performance of the TB, you best to be cammed to make full use of the increased Airflow. So currently I am just running stock TB that has been ported out a little bit and smoothed out to increase the air flow and gain a little bit more input.
I am sure there are other out there that give you way better advise and numbers that I dont have. But I am kind of in the same place you are right now
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