Is it normal for the exhaust bypass valve to remain closed at idle and with revving the engine (car stationary)? Could I have a vacuum leak if the valve is not opening?
Vafa, don't think you have a vacuum leak. Below is an quote from one of Taz's previous post in regards to when the bypass valves open on the 575.
"The 575s have a more sophisticated schedule, probably a result of the 575's more advanced 7.1.1 DME. Idling at ~ 750 rpm vs the 550's ~1000 rpm, the 575 valves are open at idle for a nice stoplight burble, close at 1000 rpm, and reopen at 2720 rpm and 64% throttle. Opening varies with rpm and throttle setting for the 575s, so lower throttle settings will result in the valves opening at higher rpm and WOT will result in them opening at 2720 rpm (as if anything was that precise)."
We later (after this post) determined that the bypass valves on 575's do not open at start up. It seems to me that you can stand behind the car and see them open with a good throttle rev but not absolutely positive. Perhaps someone can offer opinion or check this. Would do so but mine are bypassed to open at all times.
If you still don't see them open would suggest you try the bypass instructions previously posted and swap those two vacuum lines at the rear of the car. If they still don't open then I would look at the vacuum line forward of the switch (also located at the rear of the car) up to the engine compartment and make sure that it is connected to a vacuum source.
Post back here or by PM if these check out.
Also, if you have aftermarket straight pipes or x-pipes, a HGTC exhaust may be too loud with bypass valves left open. Either way you want to be sure that these valves are opening, power and sound would be missed.