No engine needs back pressure.
Really?
When I de-catted the 911 it gained serious power and torque beyond 5500rpm, made a total of 392BHP.
But between 2500-4000rpm it lost 40 BHP/Torque and could seriously be felt too, though I could also feel the big gains higher up the rpm band, but in day to day driving I noticed the torque loss more.
As such I put the cats back in to get the low down torque and power back. Also de-catted it was way too loud and would never pass track day drive by noise requirements.
Am interested in your opinion on what caused to low-down torque/power loss if it was not down to loosing back pressure m8?