That's not a bad idea, actually... limits the fabrication you have to do to merely cutting and fastening the box to the engine bay around the filter.

RE: that question about whether a heat shield is effective on the cone inside the engine bay?

Heat shields like the Simota stainless heat shield produce a noticeable difference in daytime driving, but if you sit in traffic long enough, your engine will still suffer from heat soak (something that rarely happens with a stock intake and stock exhaust manifold).

Heat shield boxes like the one your friend made, or the ones available from K&N are much better, but still not as good as full-on CAI assemblies... of course, CAIs are dangerous here in the Philippines... I've seen one dude blow an engine accidentally while using that "intercooler-look" bumper level CAI...