Recently got an A3 1.9TDI 130. I have had the head unit replaced for a Pioneer DEH-8500BT and connected in using the appropriate connect2 adapter and facia. Made a big difference to the car and added huge amount of functionality (Bluetooth, aux, ipod, SD) over the stock Audi Concert II stereo. What's the next step I should look into to make the sound better but not at huge cost? Is it to replace the standard audi front component speakers/tweaters or look to replace the rear sub or the rear speakers? My car is half amp - non-bose, no CD changer. Any recommendations for value items that would improve the sound at sensible money would be great, thanks.