Originally Posted by Corse-R

Ranier:

Much probably, your engine isn't fully broken-in. Mine STi's were a PITA to break in and one needed almost 10 litres to wake up (now is a monster).

I don't see nothing bad on your setup (well... those Skyline pipe... haven't tried, but the stock pipe does wonders, so I stick to it). Switch to a #7 Sirio plug, tried the #6 and #7 and prefeer by far the #7.

For what you're telling it sounds me that your engine isn't fully broken-in and it cannot stretch their legs too. You don't say how much fuel has been thru the P/S but.. looks very plausible to me that still lacks break-in. When broken in, the low end needle on the Sirios needs to be a tad leaner than on a Nova milll or similar, they love to go with the LSN quite lean (how much? easy... if you were adjusting a Nova, the adjustment should be 'too lean' - they need a different approach to adjusting the needles).