Tunnel Ram Tune

No, if you want to start the mains earlier, you use a smaller MAB.

I suspect your exh popping on decel is caused by a rich mixture, still burning when the exh valves open. With a TR intake, t/blades are probably closed more at idle [ compared to single 4bbl ] because you have 8 t/bores supplying air to the engine. That is going to apply a lot of engine vacuum to the idle cct on decel, pull extra fuel, making for a rich mixture.