they used the 8v valve due to space and struggled to put the 16v version in. As for fuel economy, it will get better. i believe at set miles i.e. 6000 miles the ecu will change its parameters and the characteristics of the engine will change. We do it on cars so that the engine can bed in better.
Escort Cossie Monte Carlo No81.
18" OZ Mg GRP A Rims, Coilovers
AP 6 Pots 355mm Discs, Stage 3
I'm so broke i can't even pay attention