[I installed a set on my 415 car and it sounds like the nay sayers are the ones that have not actually tried them.
I am very pleased with mine and no, pulling a hill will no open the internal bypass unless you nail it, what will open the spring loaded flapper is volumn from exhaust flow at a rapid pace, you nail it, it opens the spring loaded valve and all hell breaks loose, normal driving is pleasant and you can hear a slight rumble but nothing like the B&B I have on my other car. AT highway speed, no drone, no resonance and you can even talk on your cell phone and actually be heard and can hear what the other party is saying.
The VT's Really woke my car up since I installed a X pipe and its 3"'s all the way back from the 2" Jeal Headers.
Would I do it again, in a NY minute! If you don't want to make noise, just keep your foot out of it, that simple.
Dave Johnson has been in my car, ask him and Mark Horner has driven my car with the VT's, Twisting up the rpms will change the tone but just pulling hills or passing without going over 4K, all is rather quiet.
I used to like my loud as hell B&Bs but not any more since I installed the VT's.
Heres what they look like with 4" corsa clone dual tips.
Gibby
[IMG]
[/IMG]
[IMG]
[/IMG]