sounds like a similar problem to what I had but don't know exactly what fixed it, mine is lowered roughly about 55-60mm at the front on gaz gold coilovers and about 60mm on the rear and only knocked when turning left, I cant remember in what order but here's what I went through
made sure the tracking is bang on after adjusting the ride height and that all the strut top mount and shocker nuts were tight enough.
with coilovers what I did was when I lowered the car back down once adjusting the ride height I made sure that springs were sitting in the top seats/cups properly and adjusted the height buy measuring from the centre cap to the wheel arch and made sure all tyre pressures were the same
I also got 20mm hub centric spacers on front and I cut away bits of splashguard because from were it had been rubbing/scraping but noise when turning left was still there
my wheels are 195/45/15 with a ET26 ( I think ) with spacers 46 or so
I then put 2 new driveshafts on it but didn't cure it
checked all ball joints, track rod ends, inner track rods, wheel bearings, strut top mounts/bearings for play but were all new apart the inner track rods also in the footwells of the car interior make sure the wishbone mount nuts are tight/correct torque and outer mounting point and the balljoint pinchbolts are tight enough that they are holding the balljoint in place.
checked that the brake pipes and flexis had clearance especially that secureing clip that sticks outward did look close to the wheel but was well off it on full lock.
check that all pipes mainly powersteering were not rubbing and checked on full lock also
check/replace all engine mounts, the only one I found that was nackered was the upper gearbox mount located under the battery tray on the nearside.
mucked about with the tracking and found that the axle was starting to go on the nearside rear which did set my tracking of a tad but after adjusting the ride height until it was the same on both sides at the front and check that the rear beam was the same at both sides as well and after doing the tracking about 5 times it finally went away but now got a refurbished poly bushed axle and it handles and feels a lot better to drive. but basically it could be a one major thing or a few small things that is causing it,
check everything! whatever has got play replace or upgrade it
hope this helps as it drove me mental trying to sort it