Re-enabling the sports exhaust flap

[neil-g8km6]

I have re-enabled my sports exhaust flap today, why?
I noticed that the car appears to run out of "puff" at about 5K since disabling the exhaust flap, a reluctance/hesitance to push on towards 6K. I remembered that the plug connecting to the exhaust flap was not just a twin wire connection but a multiple wire plug, could this somehow be responsible for the hesitation of the engine past 5K?
The only way to find out was to re-enable the sports flap connection,
Result; after taking it for a test drive and once warm, it appears to have cured the problem, I have no idea why but I'm sure there are more informed members out there that could throw light on the subject.
One thing that is apparent, since using sound deadening foam to block off the internal sound resonator, there is no internal drone from the sports exhaust, neither is it intrusive inside the cab.
In conclusion, I think the best way to reduce engine noise is simply to do the internal resonator modification only.
I have uploaded photos to flikr.
https://flic.kr/p/2noKqen
https://flic.kr/p/2noN1Uu
https://flic.kr/p/2noKA5b
https://flic.kr/p/2noKA6J

[Hoofty]

Good research, thanks. It's an interesting point - the engine output is (assumedly) the same whether you opt for sports exhaust or not, so if the valve part of it appears influential to power delivery it does beg the question of if it's there on all cars?