zanda - i find the heatshield stuff to work very well. my 33 feels heaps more powerful off the line.....
Jay95R33 - i've only used the 'hand method' but im sure the heatshield is better than a metal box.
Boxhead's R32 (with FMIC) has a metal box with the heatshield inside and the box still gets really hot. i cant even touch the plenum or the x-over pipe on his 32 coz its too hot. whereas my plenum is 'warm'. certainly not hot...