Yea 282 sounds a bit low, but on my local heart breaker I made 286 with a ETUNE , same mods as you EX the Z1 manifold but I can see my AF's are all over the place so I now my tune needs to be touched up. The only part that didnt sound right was the power tappering off up top, We should be pulling all the way to redline 7500 or so. Maybe the car is pulling timing up top ? what gas are you running. If its truely bad you may want to grab some Turbo 108,
North American NA31 Turbo 108 Octane Boost - 32 Fl. Oz.
I've been running this stuff for years, ( over 20) it works.
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14 Q50 AWD, ARK, ECUTEK (SEB), Takda,