After market exhaust issues

[Rezmund]

I started a thread before on MTorque regarding the full Milltek system on my CSL. After having it adjusted due to it knocking against the heat protector (whilst expanding and contracting) I'm still having issues with noise and vibration.

When I start her up in the morning the exhaust makes a very loud vibrating sound for a good few minutes and at high revs there is a whistling type sound coming from the middle section/cats area.

I also get a lot of popping when the engine is left to decelerate or I take my foot off the gas.

Just wondering if these kinds of noises or vibrations are common place in aftermarket systmes on our cars or if I need it replacing again?

Cheers