hi, ive searched all over about the completely hollow runners(not sieseme) people have made but havent seen any results.from what i have gatherd it increases plenum area and less volocity im looking to push around 450hp out of a 383 with some nice heads(dart 200cc). if i hog the base out to like 1.75" and make a set of runners, will that allow it to breath past 4000rpm with a 58mm tb on front or should i just go carb. i was looking to get drivability and mpg out of this. the motor will more then likely see 6-6300rpm. also will see an ocasional 150-200shot thanks,

If you want the best, check out these 2 threads. We have a Group purchase going on for AS&M Large Tube Runners. Read the first thread to know what you want (few choices) than if you want the AS&M LTR's, read the 2nd thread and order.

Opinions on possible Runner Upgrade

Group Purchase Thread

if you want that many rpms out of it id go with the carb. with a good tpi setup you might see a 6000rpm red line.
PS a 52mm tb will do just as good as the 58.
but a 383 tpi with a good base and runner setup( like AS&M runner and a TPIS base),....with a good cam chose should get you 450 crank hp.
also with the heads being that large in volume youll lose ( a very small amount) of bottom end.