I added two camp mats as side insulation and two cut-outs of mat for base insulation. Whilst this improved boil vigour only slightly, it cut about 10 minutes off ramping times to mash and boil. That is about 20 minutes saved on brew day and money saved in electricity costs.
I have a 2400W element in a 50L pot. With 32L water I was achieving a VERY gentle boil. I ended up getting a cheap stainless bowl, cutting the bottom out and bam, a cheap hood. I use a hop sock whilst boiling so wasn't sure the affect a pie-tin/dish in pot would have. I showed Ross a video and he said the boils strength and evaporation rate was fine. My evaporation rate is about 18%. My pot is overly square though (40cm * 40cm) so I was losing quite a lot of energy from the large opening. Most brew-specific pots are tall and narrow, which require less power to bring to boil.
insulation
Home-made hood. I am looking to get a slightly smaller bowl so it will sit inside the pot. The condensation runs down the outside at the moment and I am getting some stains on the insulation.
Angus_grant I would leave that dome on top, as DMS evaporates you want it to drip out of the boil kettle NOT back in.
If you want a better boil try floating a metal dish on top of the wort.
I have a single 2400W element in my boil kettle, its insulated too.