at the moment I have a heater fan with a single blower outlet and would prefer to run heat to the passenger side too - does anyone have a twin outlet?

Or a Twin outlet fan? (Is the output from a twin fan MUCH better??)

Would need to be posted to the UK - so please include postage to here please

The engine compartment fan supplies some boost at low engine speeds. Most of the hot air circulation relies on the engine cooling fan. When the engine fan air output exceeds the electric blower, a flap in the blower closes and the blower spins in it's own air. From my non-scientific research this occurs about 2200 RPM. The splitter divides the air output approximately in 1/2. so the engine fan will take over at a lower RPM. There is a 911 blower fan with a splitter that has a higher CFM output but it has some challenges due to a larger size motor. I would recommend just driving in 1 lower gear to keep the engine RPMs up and enjoy the heat. Brad Mayeur

The Problem Brad is that although I live in the UK, my wife is Australian and demands that any form of transport we are in floats at around 25 degrees C. I need to get heat over her side rather than just on mine. I may think about fitting bilge blowers to up the flow instead of the stock fan, does anyone know what the cfm of the standard fan is??

That is 77 F. I do not know what the CFM is but the temp. is 77F for the people on this side of the pond.

Have you switched to SSI heat exchangers yet? They provide much more heated air than the stock ones and make the heater fan obsolete with the extra volume beyond idle...and who drives around at idle.
At 17F my windshield defrosts in about 4 blocks totally... we have had to drive my 914 this winter as a daily driver and its held up.

Actually it's only the USA that's still way behind the times on the metric system. North of the border we've used/taught it since the 70's.

Temperature in Celsius is based the metric system? Cool!

I have a dual outlet fan I put on for about a month. Just making sure all the ducting is in place is fine here with just the engine fan. Oh, and cap off the holes in the engine tin where the fan connects to.

How about just hooking up your girls side? At least temporily. You will need that hose anyway with the splitter. Maybe it will be adequate for you.