Well with all that said I guess my only response would be, you need to post the latest and greatest manual. A very big part of the equation is the manual and if it stinks eventually the whole project stinks.

As for the pitts muffler I took matters into my own hand and "remanufactured" the slimline so no firewall cutting was needed. I cut the exhaust between the header and can section, machined a hunk of 6061 to fit between them both lowering and offsetting the can section, tig welded it all together, and now the only hole in the side of the cowl will be where the header section bolts to the motor.

20 years of teaching classes relating to machining and welding helps. I guess if I were a carpenter i would have just cut the firewall.

All in All I love the plane. If you have a point at which I can download the latest manual I would sure appreciate it.