I know this has been asked before, many times, but I don't seem to be able to find the info that I want. The automatic valve on the exhaust, if this is left open what does it do to the the way the engine performs?
1. Increase MPG
2. Decrease back pressure/power
3. Makes it a bit louder, I know this one!
I've read a lot on this with all different opinions.
I would like the extra sound but not at the detriment of performance.
Cheers Rich
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