Ok,
Well i got this one completed on saturday afternoon.
No so bad really... took about 1hr 45min or so. After the tank came out i couldnt see the cracks anywhere so spent a stressful afternoon wondering if i had fixed anything and actually had cracked heads/cylinders etc.
The next day i took a close look and had a V shaped crack on the backside of the tank in one of the folds, with crusted coolant just below it. There were a bunch or other cracks starting deep inside the plastic at different locations
Mine is a 2001 so has a different tank design to the one in the DIY (longer at least).
Here are my comments to help others with the newer tank.
Take off the gas cap and the coolant cap before you start. The coolant drains really slowly with the cap in place (and really fast with it removed)
I only removed the Air Box Snorkel, not the whole assembly. Its not really in the way at all.
Remove the secondary air pump entirely. This seems much easier that tying it back. Only one hose and one connector to remove.
Absolutley, follow Lorens advice and get screw type hose clamps. Those spring type are a B$%^& to get off and im sure i could never put them back correctly. This was the hardest part of the job in my case.
The level sensor in this years tank comes out very easily. I would remove completely before removing the tank, and certainly not install it back in the new tank until its fully installed. Both were extremely easy jobs, and im sure i would have broken it if it was mounted on the tank
Remove the fuel filter. I made a real meal of this (fully removed the screw clamp, tried to unscrew the fuel lines etc). Its actually very easy. Loosen the screw type hose clamp and the whole assembly unclips from the coolant tank (clip at the front nearest you, tab in a slot at the back). The upper fuel hose is on some kind of quick disconnect running along the top of the engine bay, and the lower fuel line gets removed in the DIY anyway. The whole thing then just slips out (and dumps a filter-load of gas on my feet!)
Dremel off the tab on the tank's locating feature furthest away from you. Only one little part needs to come off, and for good measure i did the same on the new tank. There are 6 tabs and its a tight fit, so one wont be missed.
In really cant see how dropping the engine can help the removal in any way. Mine hung up on the hose clamp on the big (1.25"?) coolant tube running front to back. I loosened the hose clamp and rotated out of the way, the tank just slid right out. Sorry i cant be more specific, but i was a bit surprised it came out so quick and cant describe this any better. Reinstallation was also surprisingly fast. Tilt the top of the tank towards the engine so the lower hose parts miss the fuel rails and it seem to go right back in
I pulled the bleed valve up to fill the tank and got most of the coolant back in. After a short drive it needed a few pints to go from min to max.
So far no leaks,
Q: if the fuel lines leak you could smell this, right ? I think im being paranoid, and dont see any leaks. The quick disconnect on the fuel filter inlet came off so easy im worried it doesnt seal well.... but it doesnt leak when i watch the engine idle hot or cold.
Perhaps this can be added to the DIY if there is interest.?