Replaced mine (E34 520i) yesterday, with a set of £22.00 aftermarket ones. Original set is approx £200 (Gimme a break!!!)
The old girl had started to sound a bit lumpy, and I put a new Dizzy cap and arm on last month, so I decided to do the leads.
The only problem is the CIS, the Cylinder Identification Sensor, which is pre-fitted to lead number 6. The ring thing.
After examination of the longest lead in my new set, it was simply a matter of sliding back the rubber boot from the Dizzy cap end, un-picking the crimping, removing the fitting, sliding on the CIS, re-crimping with a combination of pliers and crimping pliers. I replaced the leads one-by-one. Two of them were knackered! The Dizzy end literally came off with a slight tug. Bad thing!.
Anyway, lumpiness has gone, the whole job...Including removal/replacement of all plugs to put the nut on the top, because the new leads require such.......took 1 hour.