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Well, I made a stupid mistake and used race gas (110) to pass emissions. I backed the timing off to ~8*, with no cats, and absolutely no emissions equipment whatsoever - and it did pass WA state emissions. (It nearly passed to begin with, idle HC was only off by 25) Afterward, the child within me took a stand and decided to take advantage of the new-found rocket fuel. I set the timing back to 15* and upped the boost to 19 (from 16 previously), keep in mind this is with nismo 555's and sport 500's, and the car was running beautifully. All seemed well cruising around town, until I got on the freeway and briefly opened it up (a pull from 50-85 or so). I didn't notice anything at first, until I had exited the freeway soon afterward and brought the car to slower speeds. The car was randomly misfiring, and would make a God-awful howling noise when the turbos tried to get into boost at all. Fast forward to yesterday when I finally had a chance to diagnose things a little bit. The #6 injector didn't seem to like the gas very much, and neither did the valves in that cylinder. Compression is fine in every cylinder except 6, at 90psi. Leakdown results pointed to the valvetrain I'm guessing the old style nismos in their stubborn ways were a bit too sensitive to the gas, causing the #6 injector to fail and lean out the cylinder under load, causing a burnt valve (I could be wrong about the cause, but it is a valve problem). This is the 3rd 555 I've had fail in 3 years or so. It's unfortunate, because I have a zetronix unit sitting on my kitchen table awaiting install, and it would have been in the car if a friend would have welded the o2 bung on when I had requested. Oh well... Live and learn. I can't stress how important it is to meter these things. I made a mistake and took a chance without the wideband, and now I am paying for it. Hopefully my slip-up can keep a couple others from making the same mistake with their Z. (Don't play with race gas unless the car is tuned for it and all things are in good working order!) It's not all too bad I suppose, because anything I may have damaged was going to be replaced here in a little while anyways. A whole new build-up minus the shortblock (already been done) is in the works. I won't divulge too much info, but I will say 3076's, Tomei, and 1200cc. RIP to the red z, for now. Looks like I'll be driving the slicktop for a little while.
See you in the garage, big red...
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PSA: Do not use race gas without a wideband - 
