The upper inlet on the center exhaust has a longer path to travel with a couple of baffles to get out.

I'm not sure if this is from a 991 GT3 but the same idea would apply

 

But the valves are attached before the entry to center muffler , I am assuming center muffler is stock. TpC design from what I can tell is similar to bbi side pipe but has a valve built in. Side mufflers due to their size provide most muffling or noise reduction. I cannot understand how adding a valve before stock center muffler helps.

 

I think what he's saying is since the upper pipes (valves) that connect to the stock center muffler are still there you're still able to utilize the baffling and section in the center muffler. Whereas a side muffler delete with a single pipe you're fully bypassing all of that.

 

right, i suspect the different with valves opened or closed is very small with the TpC exhaust

 

Actually I think it's pretty noticeable.

 

Too confusing for my taste as while. Looking at that video I'm like, "HOW?"
Im sure they get a rundown of the course beforehand though?

 

I would of been mowing down cones and pretty much lost too. I need a race track.

 

sometimes the track map is posted the friday before, other times you just walk it and learn it by driving it. i think people make a bigger deal out of it than it really is