Upgraded spark plugs on a petrol can be beneficial but as glow plugs are used just to start for diesels I wouldn't waste your money(if you can even get uprated glow plugs)
Brilliant I'm glad somebody else has tried it! Did you break the clutch down or just cover it in brake cleaner? Ye I looked at removing the ECU but I got quite good at unplugging the cables in the end!
I'm not sure how it ever got near 7.7 seconds. I've found holding at 4k to be the quickest. From no revs then setting off is mid 10s if I recall correctly.
I might have a look at valve clearances next weekend