Build header and muffler for honda 20hp?

[monkstr6100]

I have a 20hp honda in my max II. It has the factory honda 20hp muffler modified and mounted externally. Issue is is that I think it seems pretty restrictive. The header seems to be all out of maybe 7/8" OD, then into a larger flex pipe, then only about a 3/4" OD elbow into the factory muffler. Yes it's quite, but I don't mind a little more noise for more power. I was thinking of making a stainless header out of 1" OD and then have them come together into some 1-1/4" OD, then enter a glass pack or something similar. Any input would be awesome. And yes the muffler will be external again running left to right across the back of the machine, as mine is now.

[Vanguard2]

I'm interested in this project as well. I am installing an 22hp Predator motor which is the same setup as your Honda. Let me know how it works out.

[monkstr6100]

Will do. I plan to take some measurements in the next day or so and then start building something. But also need to get my boat pulled and winterize so that's priority number one being in WI and temps dropping.

[Dixon]

Look for header kit here.

https://www.robertsonstorquetubes.com/product-page/v-twin-golf-cart

[monkstr6100]

I got the header built and now need to decide on a muffler? Do I just try to gut the factory one or do I try a thrush glass pack muffler?