Supersprint Stepped vs stock Euro header Evolve review/dyno

[Obioban]

yeah the toyota and bmw heaer are not anywhere close to identical other than being a 6-1 thus are going to look kinda similar to another 6-1 from different engine inherently. they are generic in pipe size though like 1-3/4" pipe size on both like really alsmost doesnt seem to matter what engine lets make it the same lol?

I have to admit, I didn't actually look at the pictures I linked to-- I agree.

The previous pictures (back when both in side profile) were so similar as to be identical. These new pictures seem to show actually different headers. Don't know if the product has changed or if before they didn't actually have pictures of the product so just reused an old picture.

[digger]

Would the header be more appealing if it were 1 5/8? What about 1 1/2? Interestingly, the 1FZ header has options for different sizes.

I don't have any calculations or data to back any design versus another but it seems like half the members ragging on these are astroturfing for Supersprint.

modern thinking and approach for high end engines is the headers should always be matched to the exhaust port as seamlessly as possible as you’d dont want a step or change in area so close to the valve at the rpm we are dealing with and also optimising velocity and transition into the primary is far better for anti reversion than a small mismatch/dam that the ancient approach stated was ideal. If the port is way too big for the power level than even transitioning down gradually using the flange can be an improvement.

You then step the exhaust up from there every 8” or so or thereabouts depending on how much power is expected/aimed for and how long primary is needed.