Hey gang,
So I was going to post this on the tech forum, but I thought there would be more of you here to have fun with this discussion. I'm waiting on a used Box S muffler to arrive which I plan to hack into my own version of PSE with valves and a dash switch. Even if it stays on most of the time, it will be nice to have the switch option, and since my car has to pass Spanish inspection every two years, the finished mod needs to look OEM and be quiet on inspection day. Since I can TIG weld stainless, the final solution is flexible (and will be a fun project.) Though I am sure the Pedro/Oettle/Fister bypass mods are great, I'm going for a different solution.
The question is: where in the exhaust flow will the valves go? Here are some pics to get everyone oriented:
OEM muffler flow diagram (pretty sure I have this correct)
Same flow diagram from the other side
Bottom of this pic is the factory PSE from MK1 Boxsters. Note the piping from the inner chambers, through the valve. Its then routed around the muffler and directly to the tips. (This is the one that had the polished piping visible under the rear bumper)
Here is a shot of "facelift" PSE from a 2004 Box. Its not clear from the pic where the piping to the valve originates or ends up, but my educated guess is it comes from the inner chamber and gets routed to the outer chamber, where it will then go through the last curve of piping inside and out the tips.
AND FINALLY: I'm debating where my 2.5" diameter valves will go. Option 1 (easiest to fabricate) is to go directly from the inlet pipe, through a valve and right into the outer chamber. Possibly damn loud, though maybe not any more so then the usual bypass mod. No matter what I'll have to weld in a reducer from maybe 1" to 2.5" so there may not be so much more noise getting through then with 1" tubing anyway.
Option 2 is to use the valve to connect the inner and outer chambers. With the big diameter valves here I think plenty of noise will end up going through the outer chamber and then out the tailpipes, hopefully with a more refined sound then a straight-to-the-tips bypass, but I don't know. This option is a bit harder to fabricate but will not be easy to spot even with the car on a lift for inspection.
I'm open to all ideas and suggestions! Also if anyone knows a supplier for vacuum actuated exhaust valves, let me know. The one on ebay looked sketchy and he always only has "one left."
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