Update
Rather than rebuild this engine I found an excellent engine for sale. Checked the oil filter for metal shavings and found none. It was actually the 5th engine I inspected....the previous 4 had some shavings when I separated the fins of the oil filters. Some had very little but i wanted to buy an engine that had none. Next, I checked the turbos for play and oil leakage and they check out fine. Checked all the packings and seals for oil residue and all too was fine. Nothing left then but to pull the trigger !
At the moment I'm doing all the maintenance work....N20 plugs, coils, gaskets,....luckily, the engine had index 12 injectors, water pump, thermostat, belt, rollers and defection pulley, BMS drop in filter. Hardest part is waiting for all the parts to arrive.....I got a BMS chargepipe, Upgraded intercooler, already had *********, Michelin Pilot Super Sport tires, new brake rotors and brake pads, Koni Sport adjustable struts and shocks all round and a few other bits and pieces. Needless to say my pockets are significantly lighter !!
Also bought a new set of turbos off a member here.....at the moment the funds have cleared and I cannot reach him....seems to have enabled radio silence
Stage 1+ Turbos for 135i/535i/Z4 - JB4tech.com - International Turbo Tuning Discussion
While I wait for this issue to be resolved we'll start work on the suspension. When everything is finally done and she runs the way I expect her to i'll either do a JB4 or MHD tune and then call it a day on the power upgrade......don't really need more than 500bhp max.
Will keep you all posted.