Hey guys,

My built A15 is now fully broken in, seen a few track days and ran a 15.1 shifting at 4500rpm, and generaly runs beautiful under 6200rpm in my B110 4door..

Now comes the problem, as soon as I try rev her over 6300 I get an odd sound, almost like a missfire/reverbaration/ valve bounce and she stutters slightly then clears up and then at 7000rpm will not rev any higher, almost like a rev limiter.

in the A15 I have 11.5-1 comp, 280deg cam (.3mm intake and .35mm exhaust clearance), tomei dual valve springs, Tomei M-spec port layout (copied from one of the A13 touring motors) normalish header, 52mm exhaust, pertronix dissy pick up, MSD blaster SS coil, dual DCOE40's and a nice 3kg cromoly flywheel...

I have tried timing changes, plug changes (everything from range 6 to range 8) as well as jetting changes from 10.5-13afr at WOT, nothing seems to change the sudden sound at 6300rpm then total drop of power at 7000rpm

Here is the million dollar question:
1. Exhaust back pressure is to high
2. some form of intake reverbaration
3. Faulty pertronix?

Any idea's guys?