I would consider looking into fitting vct to an rb26 head, then you could do intake and exhaust cam timing. Use neo cams, rb25 cam pulleys(or evo ones if you want to get tricky). IMO the nissan vct is primative in that its either advanced or ratarded, nothing in between, wheras almost all newer vct setups are true variable control. Thats where the power is.
I would run a least a 3/8(10mm) internal diameter return line. What reg are you going to use. There was a guy on here last week with the same setup, and had issues controlling fuel pressure. I hope you are running 1200cc injectors to make use of the overkill fuel system. I think you will definately need a fuel cooler as well.
NO you read right, gtr turbos kill motors, wheras gtst turbos dont. Could be due to the manifold design, cam timing, maybe because the gtr turbos are smaller, they spin harder and fly apart harder, who kmows.
Im surprised, usually with the stock default map they detonate out of th ebox. I wouldnt lean on it too hard without a tune. Remember a stock setup detonating can crack a piston easier than a 350rwkw well tuned setup.
I cant remenber as i sold my hks pipe, but if you slide the top silicon all the way onto the hard pipe, fit the pipe to the lower silicon and then slide the top silicon up, does that make sense?
Its a gamble, but not really a cheap one, they dont have any warranty, so if it dies in 2 weeks, you are $800 down. If you have that sort of money to spend, i would get a holset hx35 and get it rebuilt, should be around $800
I would do a comp test first to see if anything is damaged. I cant imagine you could hear a spark plug tip rattling around in your cylinder. If it came off in your motor it would have melted off so either the damage is done, or it has come out the exhaust. A comp test will tell you if it has damaged the valves/bores. If the comp is good, i would keep driving it.