Yeh - the clear silicone spray you would put on doors and rubber.I just used it as a dry lubricant for the piston. For the clacking sound - 2 things - how many miles on the car? Timing chains are usually good for 200,000 miles - the plastic chain guides and tensioner are the real problems to look for on this and the 420 engine. They should be done every 100,000 miles for peace of mind. The plastic guides and tensioner are cheap and if you do a search on this site Mike Tangas posted a real good article with step by step instructions on changing them. I think my tensioner and guides came to about $70. I changed my chain at about 160,000 miles and found I didn't have to - there was no stretch in it at all - when I held it by one end and lifted it it had the same amount of sag as the new chain. I don't think the clacking is chain though - more likely lifter sticking. Is it always there? always the same cycling? or does it clack in cycles and disappear and come back again randomly? I only drive my 560 occasionally for fun - not daily - if it sat for a month or so and I ran it - I had a little clacking sound on the passenger side bank from a lifter that went away after a 2 hour cruise. I used a can of Wynn's upper cylinder lubricant in the oil (says it quiets noisy lifters) and it slowly went away. - For a couple of bucks worth a try. If the noise stays there afterwards - then suspect chain or guides. From what I have read -normally chains make noise when cold and just starting up and tends to get less as the engine warms.Mike's article tells you what to look for on the plastic guides before changing - if I remember right - if they are the color of beer bottles - change them - new ones are white.
As for the filter - how can it change the fuel pressure? Once it is in the line nothing else is different. One suggestion though - I don't know the fuel pressure on this car - just check and make sure the new filter will operate at the pressures of this system whith the supply store you buy it from and you should be home free.