I want the best possible system I can only utilizing the existing speaker holes and the space under the seats. But here is the trick I don't want to change out the existing head unit because I want the interior to remain as stock as possible. I was told the Alpine Type Rs are the best speakers and if I got 1 4 channel alpine amp that would sounds great. Any advice... I don't really car how much it is going to cost. NO sub in the boot either.

 

Are you going to do the install yourself?
You might PM Scooterboy, he did a nice job with his install.

 

Details and pics of my install are here.

I had originally bought an Alpine MRV-450 amp to put in the cavity under one of the seats, but once I found the Clarion sub, I didn't need the fifth channel. I think it ended up better with the two blaupunkt amps as I didn't have to cut as big of a hole in the carpet as the Alpine would have required.

If the only reason you're keeping the MINI head unit is in order to look stock to potential thieves, check out the "stock" faceplate I created. If you get a new head unit that folds up flat, the faceplate can be stuck onto it and it will look stock.

Check it out here.