Hey there.
Finallly, after a long 2 months saving, I was able to install a custom made ex in my /6. It has 1 3/4" primary, 2" collectors and 2 1/4" to the end. It's 3 to 1 + 3 to 1. I can't tell you how happy I am. Not only sounds great, but revs up much more faster at lower throttle opening, has more power. I gues that the original 1 3/4 original pipes weren't enough for the engine... now I have special cam, tweaked carb (1 bbl but more cfm than a carter 2 bbl) shaved block and head. Runs like I always wanted my /6 to run. Does somebody knows how much ponnies a good ex can add? I feel a lot of diffrence, and not only in the sound. I even feel a diffrence in the shifting of my 904... but that may be just illusions

Headers can get you a 10-15% increase in HP.
In your case, where the cam and intake have also been up-graded, you will see even more increase. You probably gained 20 to 25 HP with your swap but most of that gain will be at higher RPMs.
DD

Thanks Doc. I really considered on buying your duals, but as I told you in another topic, getting that kind of heavy goods is a li'l tough in this country. I'll post a picture of my ex, so you can see how I solved the heat riser thingy and tell me what you think about that.

Thanks again for taking time to answer. Juan.

pix

That's a good 'cheat', although I'd worry about long drives creating a 'heatspot' in the manifold. If I lived in Seattle or in the snow-zones that's what I'd do....

Other than that your exhaust system is "muy bonita"...

-D.Idiot

Thanks! i've drive tested that to ensure there's no hot sopt at all. After 3 hours driving in town (the worst panorama ever on a slant 6 for heating issues) the fuel was warm yet not HOT enough to bubble inside the carb bowl. Inside the "leg" the diameter is smaller, that leg is made outta 3/4" perforated solid stock, not tube.

Those are purdy looking bends. Do you have access to a hydralic bender?

Yes, all the bending is made with hyd benders. I used a friend's bender (he has an ex shop) and expert hand with that tool. He has been making sport exs since 1959.