Indeed the Caterham RBTB fit under a SV bonnet without needing to cut a hole, but if you ever want to quiet them down with a "trackday intake" you'll run into problems. I also get pretty bad heat soak or vaporisation or something - runs fine until you park it up, leave it long enough and it's fine, take the bonnet off for a bit and it's fine, otherwise it coughs, splutters and tries to die for a few hundred yards until a bit of airflow gets to it. IMO the standard map is pretty rough and I'd certainly not recommend fitting them for reasons of idle and smoothness. Nothing a remap wouldn't sort but still. I think I'd be tempted to leave it until the warranty expires and look at all available options, unless keeping it Caterham original is important to you.