Had another thought - Ottie - you could try taking the separate exhaust cooling line off. Connect the output line for the head to flange (use only one cooling line for head, flange, and pipe). This may give you a little more performance, albeit marginal, maybe not even noticeable. You will burn thru more O-rings in the pipe wtih this setup.

ottie44 wrote:Here's my steel pipe system setup on my 41" cat, as you can see, no leak flange, 90* header, 1" band pipe and T-mod muffler, 450 degree hi-temp O rings. What prop are you running? I'm using a Bob Austin mod 667 and Chris mod 2716 15* cat props, they run super fasssss.

Thats my next step! One pickup for cooling. To the head first, then header, than pipe to see if I can raise the BTU's. The engine temp should be around 180 but any idea on the header or pipe temp? With dual pickup the header has never been hot enuff that you can't touch it! Running an X667 two blade Texas cut!

I measured with a string down the middle of the header to pipe and it measures 13 1/2 inches. I also made sure that the header didn't go any further than a 1/2 inch into the tuned pipe. I got the idea to use a string from Tony at Warehouse Hobbies on measuring pipe length. Do you think I should go shorter than that?

To give you an idea, I run one pipe at 290mm and another at 305mm, that's 11.5" & 12".