This is what i ended up With! I do'nt like threads that do'nt have a ending, so i just wanted to say my experience.
This Project took time, i went to multiple exhaust shop's, at first With the valved idea.
The cost if a shop was to do this was so high that i instead bought a sheap mig welder. I had no previus experience with weldig, but with some training on test pieces i mannaged to get a good but not to pretty weld. I figgured the walves was so big that fitting them was too mouch of a hassle for me with my experience. I was looking for walves in about 1 inch size, but could not find any. also they should have had the design like the vacuume ones. I also cut of the oval pipe and welded on round ones that are sticking more out (flush with the bumper). When i had all parts and made my desision how i wantet it, it was only a short day of work.
I went with 1.25 inch pipes. The sound is ecsactly what i was looking for on start up. Betwen 2 - 3000 rpm it's alittlebit too mouch, InFact this is where you have most sound. Over 3000 it's reealy good! There is no drone but engine / exhaust sound is in owerall littlebit higher. The more you push the pedal the more sound, drive easy and the sound is not too mouch. It sounds like a real Carrera and propper Porsche!
I think i would have went with 1 inch pipes if i were to do this again. Because you have allot of sound betwen 2 - 3k rpm (also when driving "normal") it sounds like you are going faster then you actually are.
This is my opinion, age 24. I'm also on the hard top now, Winter in Norway so have'nt driven the car top down, only windows down and its a noticable difference, so exited to dive it top Down next summer