340 HP's vs headers

I have the Hedman Tight Tubes for my Duster, they install easy enough but good luck getting the exhaust hooked up; I had to fab my own downpipes that snaked down off the flanges, up over the steering linkage, then back down to the rest of the exhaust. Very time consuming, and in the end it still looks like you have headers in your car lol.

Manifolds suck because the exhaust pulses from each cylinder smack into the adjacent ones, on stock engines it doesn't matter because the cam overlap is too short for it to make a difference but put any kind of performance cam in it and the engine is basically working against itself trying to push the exhaust out, instead of it being scavenged out by individual header tubes.
I know the manifolds hurt performance a bit, however i cannot imagine rhe hi po ones killing a strokers power 100-150HP like my machinest says they will. He's prob used to SBC manifolds doing that, and admits he doesnt know too much about mopar factory hot rod parts especially the 340 hi po mannys. I plan on using a mini denso starter, and using longer C body idler and pitman arms to speed up the ratio. This will move the center link back a bit, maybe that will give me enough room as a work around with shorty headers, if i go the tight tube route, i will prob mock it up as well before blowing the car back apart for paint.