Exhaust question - Midpipe with ZCP muffler

[///M-pressed]

Hey all, I tried to research this as much as I could, but any help would be greatly appreciated.

So I've got a ZCP (M4 pure over here) and rather than spend big dollars on an exhaust system, I've whacked on a non-resonated Remus midpipe to bolt up to my ZCP stock muffler.

Sounds good, but for the life of me what I don't get is that sometimes on partial throttle it's super quiet and you can barely here the exhaust noise of the car.

My question is:

Is it something to do with the valves not being fully open? I've put the car into sport but do the valves not fully open until you press on the accelerator more? It gets louder as the revs build which makes me believe that may be the case.

Any insight would be greatly appreciated.

[ntg44]

There's a thread on here somewhere, but if I remember correctly, in Sport/Sport+, the valves stay open in 1st and 2nd, and close in 3rd gear+ to prevent drone. Even then, they aren't "always" open in 1st and 2nd. When I unplugged my valves to permanently stay open, partial throttle was noticeably louder.

When I had completely stock exhaust, unplugged valves with ASD off was my favorite configuration. My only complaint was that my manual shifter would rattle a bit around 2500 RPM more or less. Replacing 2nd cats with resonators fixed this completely. Cold start is also a tad loud, but it was worth the trade-off to me. But partial throttle is definitely what I'd want it to be in a car like this now, even before the resonator swap. Not sure how this would be with an aftermarket mid pipe though.

[dsmclark]

get bootmod3 and you can keep the stock map and set the valves to always be open in sport! Also can delete cold start as well

[///M-pressed]

Thanks guys for the help! Just what I was looking for.