Freelander 1 Re-plumbing the st'd PRT installation

The heat output from my heater is very poor in cold weather. I watched a presentation from 'comeinhandynow' on youtube. see here. It explains why the heat output is poor and how it can be improved. Has anyone else on LZ looked at this. I'll have to rewatch it a few times to understand it better... Any pitfalls that you can see?

How bad is the heater, I'd look at heater matrix being blocked first, but the heater should be nice and hot. Flushing can push gunk into the matrix wgich may or maynot be able to be flushed out. What sort of lower temps do you get? Then any modification to help.

When I flush the heater matrix, water seems to pour out OK, so I don't believe there's a blockage. Possibly my 1.8 is very well cooled!
The radiator is quite new, less than 4 years old, new coolant pump & coolant... 2 months ago, replaced the coolant bottle for a VW one, as in comeinhandynow's post on you tube. I also run an oil cooler via a thermostatic take off on the oil filter mount.

I'm thinking about blocking the air flow to the radiator with a piece of card to reduce the air flow to see it that helps with a quicker warm-up and more heat output from the heater...

The heater matrixes on Freelander are notoriously leaky - mine is a prime example. If you clear the crud out of it, I'm sure there's a good chance it will start leaking!

As replacement is a painful dash out job, I've been wondering if the air could be heated by a matrix of some kind before entering the heater box (ie in the engine bay) and the standard matrix in there bypassed. Should say, I haven't investigated where air comes from to the heater heater box and whether its possible to site a matrix along that 'ducting' anywhere.

As you're an experienced hand at plugging other car's components into the Freelander's cooling system, just thought I'd throw that 1 in there