I run IHRA J/CM (crate motor) @ 3,540+ lbs, in which the 360 has better specs than "regular" Stockers. But I've "only" run a best of 11.14 @ 117 on a 12.25 index. (There are some "regular" Stock 340's and 360's as fast as mid-10's.) I also have an NHRA 3,800 lb J/SA 360 Aspen wagon which I'm still sorting out and eventually expecting around 12.00 on a 12.45 index. All VERY rules-restricted.
I somewhat recall an article about Joe Sherman and what was a pretty fast, but possibly somewhat unconventional Nova. But no rules.
Yes, time and budget limit my testing. Custom headers are definitely out of my budget, so off-the-shelf will have to do. It was over 10 years ago that I switched from the 1 7/8 headers that came with my Dart to the TTI 1 5/8"-1 3/4" stepped. All I can say is that if I didn't see a positive difference in my particular application, then i would have switched to 1 7/8" TTIs since then. Although worth considering, to compare them now isn't feasible at this time either . But as mentioned in another thread, adding an X-pipe and UltraFlo mufflers helped what I have. I have heard of a few other fast small block Stockers, that have more time & resources, use TTI stepped, and in some cases cut the original collectors off and installed the merged versions.
I hate to fall back on that old saying that "each combo is different", "your results may vary", but it still does apply, whether it be steps, diameter, collector style, etc. Too many variable for a clear answer for everyone. Racing, like life, if full of compromises and you do the best you can within your limitations. I won't be among the fastest, but I'll get as close as I can.
I've also spoken with some fast Stock racers who have used even smaller primary exit pipes, sometimes actually port matched, but then stepped up 1 or 2 steps, with claimed good results. But even "good" has it's variables. Some Stock racers will be ecstatic with a .05 gain, which can often be within a margin of error to most people. Depends how many variables were taken out of the testing.
As for cam lobes and their relationship with the rest of the combo....I have to rely on the cam companies for specs based on what I have and then adjust the rest around that afterwards looking for gains.
Bottom line is that I barely have enough time to establish baselines and test with what I have, much less to be swapping parts, changing cam specs, etc. But when I do have an opportunity, I do the best I can. I just wouldn't say something helped me if I wasn't sure it did, even with a margin of error.
