So, good news bad news (i.e. all change) -
Good(ish) - The ceramics seller dropped out which gave me some money to spend.
Bad - My new work contract took a slight pay hit so I've had to compromise on my spec list.
So instead of 900hp in spring I've got my car booked in to MRC in Dec for 800hp and 900hp will have to wait until late summer.
Just to keep me happy though I've fitted the 3in cat-back exhaust now - WOW!!!!! A much deeper sound than the stock with back-box removed, much smoother (less harsh), quieter at idle (good for my neighbours), the gear change "farts" are now all snappy/crackly explosions although, being non-resonated, it's a little droney (my biggest fear) at part throttle (hills etc) so I'll be adding Resonators
Now I've done it I wish it had been the very first thing I'd done now, it's that good. Fitting was a bit of a pain (needed to go back twice for very minor tweaks -still needs a final tweak) but it's a much better sound than messing around modifying the stock one.
To be fair the modded stock did sound better at idle-1500rpm (5-10mph) as the harsher sound was more noticeable buts as my new exhaust is modular, I can easily remove my back-boxes again by un-doing 1 clamp on each box but I can imagine that being stupidly loud.