Thanks for the responses. My assumptions have been gained from reading around a 1000 pages on this forum. Happy to be corrected. I am learning a lot from you guys.
The problem as i see it is there are thousands of different routes to get to the same outcome. A system that sounds good.
I keep hearing Jeherts as a good options, but can not find anyone that sells them in the UK.
The MB quarts i have bought for example have no reviews on here. I have heard people say they are not good, but no one has heard them so i thought i would give them a try. They will be a massive upgrade to what is there and MB quart is a quality German company so there products should be good.
For sure my system will have some compromises in it as i don't have unlimited budget, but i hope to have something that sounds better than logic. I am also very keen to have a system that can be removed with no signs.
iB set up does indeed look good. In fact i am considering doing this in my 635csi, but i have two concerns. One is that cutting the car will affect resale. Not an issue with my 635 as i will never sell her. The other is that cutting the car will affect ridgity of the car and i like to throw a car around. Again not an issue with the 635 as it's floppy anyway as it's very old.
The beauty of the underfloor is that it's non invasive and understated allowing full use of the boot. Yes it won't sound as good, but i always prefer a sealed enclosure as it gives a very tight bass.
E90 330i SE Auto Graphite Grey Metalic