I have had several weiand intakes with 500, 600, and 650 cfm. The 650 Edelbrock worked very well with the aggessive Erson cam and valve springs. Mopars/GM HEI ignition. I did have flow thru dual exhaust with that combo. That particular 650 combo did not give but 15 mpg on the Highway but it did haul the mail.

Anyways, I did find an "estimated" 60 hp gain. How do I know 60+ hp was correct without a dyno.?
For one thing tons of competitive experience,.

However considering I was an elder statesman at this time of my life it mainly was from 350 chevys at the light. After I blew their doors off, I patiently waited and when they caught up to me they would say,... What the hell ya got in that thing,! A 440? When I told them a 318 they thought I was full of shit, just like a couple readers probably do.

BTW several attemts by "other" General Motors were made. The word got around in the small town so I was challenged fairly often.

These accelerating events were often verified as to the chevys having 350's with four barrels. In other words the poly hangs out well with bigger brothers.

Few of those Chevys were 3/4 tons and most often weighed less than my 4600 pounds.

I just couldn't help but comment,
BTW, that D200 was nicknamed "Frame Twister"

For even more HP put on Norms DTA headers.

I don't like to do this hunt and peck typing, with bad eyesight but I just had to say,..

Gordo