Not sure, realised just after I put it in that I should have weighed it. Nevermind.
Anyhow, finally the car is going again.
After spending a couple of hours on Sunday morning rolling around on the wet ground trying to get it done, I had it about 90% finished but couldn't get it done as the previous day a friend of mine was over and was kind enough to push the clutch pedal, dislodging the piston from the slave cylinder. I didn't realise this and spent a good 45 minutes in a lake trying to put it back in, with the rod not budging, only to realise what was going on. Luckily, my good friend Ben came to the rescue that night with a replacement one which I went to pick up. Yesterday afternoon I got back to it and got it back together. The improvement with this flywheel is drastic. I almost couldn't believe what a difference it made, but then it does make sense. The car takes off so much faster than it did before. Anybody with an M30, if you want your car to go faster, I seriously suggest you track down a single mass flywheel, no matter the cost. It's well worth it.
Over the next couple of days I have a few small jobs to do on it like replace the front bumper and some small engine related stuff. I'm just glad it's going.