408 stroker exhaust question

ok - been running my truck last summer and started the other week driving it this year with the rebuilt 360 (thanks to FABO:prayer:) , works good but i'm already planning a 408 stroker build, with a target of around 430/450 horse range .

my question is I am using a set of newer magnum short headers which are 1 1/2 tube diameter and 2 1/4 head pipes and tail pipes (its a red express so i'm using the factory stacks which limit the tailpipe diameter). How much horsepower loss would there be with the stroker with this choked exhaust?

the other option would be the hedman tight tubes ( 1 5/8 dia) with 2 1/2 headpipes and 2 1/4 factory tailpipes with the stacks. would this increase in headpipe diameter make that much of a difference with the smaller tailpipes to warrent the extra money to change?

or should i just run full lenght with 2 1/2 pipes under the truck and mount the stacks for show?

what do you think - thanks in advance as always - Jimmy