On a street/strip 440 A body, is there a big gain to be had going from the 1 3/4" TTI headers to the 2" TTI headers? My combo is a .030 over 440, Stage 6 heads ( ported, non- max wedge ), .588 lift Comp solid roller, Harland Sharp 1.5 rockers, M1 single plane, HP950 carb, 727, converter to be named later, 4.10 rear in an all-steel ( except for the glass hood ) 68 Dart. Just curious to see what you guys say. Does anyone have a header / engine sim program to run it through?

I was going to say I would like 1-7/8 headers on your combo. I can tell you I run 1-3/4 headers on the 906 headed .557 cammed 440 in my 63. It has run 11.50's as a street car driver at 3700 lbs. I think my combo is fine with the 1-3/4 and may not pick up with larger tubes. I am sure some others will chime in who have tried both sizes. Ron

I'll take a s.w.a.g and say the combination you described will make about 20 HP more w/ the 2" headers. FWIW, I have the 2" TTIs on my Challenger.

We see gains of 3 to 9 hp with 2" over 1-7/8", and about the same with the stepp headers.We have see a loss in mph with anything bigger than 2-1/8 on a 500" or less wedge.