Exhaust header ?
 

Question : on the Ls3 engine the exhaust
Header from GM etc is 1.7/8 inch diam.
Due to restricted space it seams that
You can only use 1.5 inch diam. Tube on the
Miata.

Does that do any harm to the engine...
Head...or noticeable performance !
Does the restriction cause a overheating of
The head ?

Thanks in advance
TVP

Theoretically, yes, it will cause it to run hotter. Reality- I've not seen any added KR. Now the dented headers will cause the one cylinder to run hot. The old headers guys had to run were dented on cylinder number 1 and sometimes on 7.... And they were BASHED in!

My kit from Boss Frog had the Hooker shorty headers so they cleared the steeering column with a little dent on the collector but none on the tubes. I would love to see some long tube headers put on a LS motor as I'm sure I have alot of back pressure from the restricted exhaust setup. Not much room to work with there.