Shorties won't help but looks like you're fixing that.

The FM exhaust might help a little but the 160 stat doesn't really.

The 6.0 T/B is the exact same as any of the same smaller V8 T/B's from that style and the stock MAF works best at your level.

The Diablow is not up to par especially combined with the aftermarket MAF. Put the LT's on as well as the stock MAF. Get a Nelson tune and sell the old T/B and the Diablow on eBay.