Depends what you are trying to achieve really. The set-up on these is a floating pulley, so technically you dont need vernier pulleys, so really you could tweek the timing using power runs since you dont really have a lift@tdc figure to work from for stock cams. That sais, whether you will see a gain is questionable, ive not tried on std cams so cant say. Youd likely pick up somewhere along the lines.
Best bet is just make sure its timed correctlyas according to renault locking tools etc.
With these engines, they have infinately adjustable cam phasing on the inlet cams....this feature is fantastic for optimising through the rev range, so IMO to fit a pair of verniers and ditching this facility is sacrilage! So even with aftermarket cams, best bet is timing to manufacturers lift at tdc initially, then tweaking on the dyno.
Its never simple and its never quick, but for best results its the only way. From experience as a Catcams dealer, their lift@tdc figures are pretty good, but depending on the application we often deviate from them.
