Sorry about the long wait peeps, I've been trying desparately to get my pics uploaded and only found some time today, so I can start with the re-learnin!!
If you can find polycarbonate at a good price it might be worth trying, I think you'll need more heat but in the end, once it's bent it's bent!!
you do use heat to bend them, and if you do it right, all will come out relatively well, around 300-340˚ works nice and quickly.
Here's my secret weapon.
It's a peice of silicon tube, it's flexible, doesn't stick to plastic, and keeps its roundness when bent.
I attached it to a peice of wire (press fit) and put it up the tube
I'd then set it in the position I want it to be in (you can see the black mark for where the bent centre should be) and then I heat up an area 2-3 times the diamter, so, say for 3/8" tubing I was doing about an inch, but for 3/4, youd be looking for at least 2 1/2" minimum.
Heat it by rolling the tube and making sure you have even heat, (wear a heatproof glove on one hand at least!) when it all goes soft, and starts to bend under it's own weight, put it in the position you want it, and wait till it cools.
you should have a nice bend if you got it right.
then, slooowly pull out the silicon tube, and you should have a nice clean bend.
Silicon tube is used in model aircraft as fuel tube and exhaust couplers, I fly planes so I have a stupid supply of this, and the thing is, you can do it again, and again, and again!!!
So there you go,
Oh and to see the final piping run, this is what I did.
here's the intake tube.