It has come the time to change my timing belt, since I have a Focus there are all sorts of goodies to make my car go fast and get really bad gas mileage, that is until I saw a pair of adjustable timing sprockets. Would the mileage improvements be worth the investment to have the ability to retard my intake cam a couple of degrees?
When I was a student I remember reading a thesis from two students who wanted to test different positions of the camshaft. I remember the vehicle was a small Fiat, with a small petrol engine DOHC, carburettor.
They could not adjust the camshaft while the engine was running, but they could very easy just change it a few degrees. After each adjustment they put the engine on a dyno and measured torque, BHP, fuel consumption and emissions on a range of RPM's and engine load.
Very interesting conclusion: NO gains could be achieved, on no matter what field when you only adjust the camshaftposition.
On engines developed by R&D-departments with variable camshafts everything is adapted to go with it (fuel mixture, ignition timing, EGR, expected lambdavalue, drive by wire throttle housing,...).
I know e.g. the variable exhaust camshaft on a European Honda TypeR's main function is EGR. They did not had to install a classic EGR, but by delaying the closing of exhaustvalve you suck in some exhaust gas....there's your EGR.
A question raises: aftermarket camshafts have most of the time only one goal: more power by more valve overlap and higher valvelift. If this is the case I would definitely not do this.
Based on this (limited) info I would not go for this modification.