I have an E36 328i, and have had pipe fitted by the van der Linde boys. It cost me about R4800. I know one of our other members, edwich, has a E92 M3 with a van der Linde pipe on too, and he sounds well chuffed with it.
I am happy with my power gains, but not entirely happy with the sound. The car tends to drone a bit when driven sedately... :cursin: (not that that happens too often

)
I believe RG's pipes are less noisy and pretty good, but pricey.
As for the AC's, try 15k for just the rear sliencer! :shocked: :dropjaw: