So after some investigation it appears that the whistling noise is fairly common. Also double checked the for manifold leak and there was none. So for those of you planning to mount flatslide carbs.......if at part throttle you hear a turbo style whistle don't be alarmed.

Tom

Naturally aspirated 4 cylinder push-rod A-series with a slight turbo spool-up whistle?? That doesn't sound too bad! Thanks for reporting back. I'll look into FCR/MSR carbs next year I reckon.

It does add to the aura of flatslides...................but as mentioned, aura doesn't do diddly for lap times..............then again as your hustling through a big sweeper at 5k, a car that makes the right sounds is part of this as well. If it were all maximum lap times I'd have thrown the 1200 over and went back to a single seater at least a year ago.

Tom