i have the evo setup with dps and wireless kit:
1) basically what artemis said. however i think it depends on your dealer. mine doesnt mind me running the evo with dps... and i still have the warranty.
2) dps make a huge difference with regard to noise and smell. i doubt you'll notice a big change in power if you run with the dps or not (however you will most likely be required to do some coding with the dps).
3) id say with the valves closed its quieter than stock. however, ive noticed that if i open the valves, drive around for a couple of miles and then close them again, the akra sounds louder than if i keep the closed from the start on...
4) i do have slight difference in spacing between the tips and the diffusor (left and right). but then again i dont run the stock diffusor - so i blame that
5) see question 2)
6) and 7) dito what artemis said
hope this helps you. IMO get the evo with dps
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