Hi Boys
The 911 Zeniths (TIN's I think they are) would be OK for the PRV - except for one thing - a manifold. Unless you know of one lying around, have someone who can modify and weld a standard aluminium one, or have deep pockets, the manifold cost could easily outweigh any decent advantage you may gain financially. And that's before you recalculate increased fuel costs.
A friend of mine in France has a triple Weber setup on his A310. The car goes like stink, and returns around 10-12mpg when he exercises the loud pedal. Well you'd want to, wouldn't you?
If yours is a 'second' car, then go for it and enjoy to the max.
Just thought I'd mention it.....sorry!
a310man