[Chevy454]

A few thoughts...

First off, those are really good numbers! Has anything been done to the engine? Any idea what cam?

That HP peak sounds about right for an LS-6 through manifolds. Mine peaked at 5400, and somewhere earlier in the thread I think someone posted that's about the neighborhood it's supposed to be in. An L-72 peaks about 300-500 higher due to it's shorter stroke, but doesn't make near the torque the LS-6 does.

As for mufflers, skip the Flowmasters and go with the Dynomax units. I've got the part number around here somewhere, but they make an AWESOME muffler for the A-bodies that will outflow that Flowmaster and will sound TONS better as well. It's what I've run on my L-78 and my LS-6, and is what the majority of the Pure Stock guys run. If I can find it, I've got an unbelievable exhaust test done by the Buick club that raves about this muffler...

You are correct in thinking all the little things (carb, valve job, etc.) will help, as it all adds up. Be careful and get the original type Pertronix unit and not the later model. Trust me, you don't want the newer style.

Again, AWESOME numbers, and I'd love to see what that thing would do on the track!