Big mistake.......for several reasons, not the least of which is that bikes that have been "screwed with" by an amateur often don't run right.
I have a yamaha vstar classic that has after market exhaust and the karyokin hypercharger.
A high, unstable idle is often caused by a vacuum leak around the carbs.
The hypercharger itself might cause this if not properly installed.
In your case, it sounds like the throttle mechanism or cables are binding.......or a return spring is missing, broken or stretched.
Or something with the hyhpercharger is binding the throttle.
My advice is to find a stock air intake system first and junk that hyper-crap thing.
Oh, and if those pipes have no baffles in them, I suggest you replace them too......but mostly for a different reason.
'07 Honda Shadow VLX 600