The clacking, TOD (tick of death) is what drove me to buy an outback. Granted, I bought the outback with the first gen DOHC and had head gaskets problems.
I owned a RX and a GL-10 Turbo Wagon.
I tried everything under the sun to relieve the TOD. I rebuilt the lifters, new oil pump, new seals, every oil from 0-30w to straight 30w, a quart of ATF in the oil, sea foam, other "sticky lifter" products and none of them worked. (I tried every remedy at different times, never two at once). The only thing that caused a pause in lifter noise was me being willing to write the engine off and tach it out to 10+grand RPMS for 3-5 seconds at a time, that would last about 50 miles. I did have luck with the stuff called CD-2, in my Outback.
I just got done reading your thread about trying to get power out of an EA82t. I had 2.25" inch turbo back exhaust, Intercooler, intake, and a dual core radiator and still had problems. One of the first post I ever read here was from WJM. It went something like this "Cheap, Reliable, Fast. Pick two." Another words. Cheap and Fast isn't going to be Reliable. Reliable and Fast isn't going to be Cheap. Cheap and Reliable isn't going to be fast.
Don't get discouraged. Do what you want. It's a good learning experience, if nothing else.