rnl

it is my understanding that the backfire sound occurs when intake and exhaust are open at the same time - an overlap

rnl

I have a C2 and, while it accelerates from stop quickly, I am more impressed by its acceleration from 35mph up

Colvin84

Slightly off topic - but is PSE standard on the 991.1 S or an option? I bought used and have PSE but it doesn’t show up on my vinalytics.

malahhaor

No, PSE is never a standard option. S does have valves on a Non-PSE exhaust but its not the actual PSE muffler. The valves are automatically opened at higher RPM and you don't have control like you do with actual PSE.
Here is something i just threw together for reference. 3.4 image is actually from 991.2 but its almost identical to 991.1 just without flanges that connect to catalytics:

Colvin84

Thanks. Must have been added to my S after initial build.

rff15e

Even some older Porsches can "crackle and pop." It depends on the stroke, how their injectors are timed, valve timing/overlap, EGT, etc. However, you typically can't hear it with a couple muffler stages, etc. It's not just a "race car thing."

All said, it's a little more complicated than just "pouring more fuel into the exhaust."