Got my power back!
I've finally got round to replacing my bottom intercooler pipe to match the top one I did a couple of weeks ago. Instead of silicone all the way I used aluminium as much as possible with silicone as joiners and to give some flexibility. The difference is superb. More power and cleaner spooling really make it necessary to watch my right foot. The bottom hose was so soft, oil soaked and degraded that I think it must have been blowing up like a balloon!
I bought a hose selection box from eBay but had to add two silicone 45 bends and a reducer to it. In all, top and bottom, I used two silicone 45s, two alloy 45s, an alloy 90, a 57 to 51 reducer, three silicone joiners and ten hose clips. One alloy 45 had to be extended by four inches so if you haven't got a tame welder that would add another joiner to the list - the extension was an offcut from one of the 45s. The leftovers from the kit - two straights, a 90, two 110s, two silicone 90s three joiners and some clips will go onto the "that'll come in handy" shelf for future projects.