Latest Update, re jigging the 'tap off' lines and i think i've nailed the correct setup. my most recent mistake was leaving the crank case breather connected to the intake manifold lines. i'm all for crankcase breathing and agreed that yes it's better to have the vapours sucked out then to leak out after the pressure built up. however due to the high vacuum caused from the ITB setup i was actually leaking air in through my breather, into the rocker cover and through into the manifold. this caused my MAP sensor to read partially open when the TPS read shut. having re plumbed that the response is a lot more lively through out the rev range as it's no longer running uber rich for an N/A. also worth noting for those that intend to run N/A E-series engines. alot of people complain about how the standard valve springs are no good for higher revving applications. well this might be true if you're trying to enter 4A-GE territory but for up to 8000 the standard ones shouldn't prove to be a problem. the evidence i use to back up my claim is that the higher revving 5E-FHE engine (redline at 7400) uses exactly the same valve springs (identical part numbers, both compression spring: 13711C-90504‑34001 and the retainer: 13741-13741‑16010) as those found in any 5E/4E head.