One problem with using the GT-Four RC intercooler set up is that it has no Air Bypass Valve (aka BPV, BOV). Installing a BPV isn't a major issue, however since I want to use a plumb back type rather than a nasty noisemaker, it made a bit more difficult. The layout of my intake piping meant that the plumb back return line had to be fitted to the outlet of the AFM, as there was really nowhere else to put it.

The first thing I had to do was to get a flange to mount the BPV to. Some people just attach a hose to the base of the MR2 BPV but I wasn't very happy with with that as there's only about 10mm to grip onto, so I cut the flange off the factory IC pipe and milled it flat to tidy it up. Here it is mounted to the BPV

To fit the flange to the intercooler I got some 30mm aluminium pipe and scallopped it to fit around the radius of the IC inlet

The same was done for the AFM, where the plumb back fitting would go. Also as I was going to be eliminating the factory rubber pipe that was joining the AFM to the turbo inlet, I had to put a fitting into the AFM for the idle air. The fitting is a 1/2" brass hose tail with a 1/4" BSP thread which I tapped into the AFM.

So having prepared all that, it was off to trusty ol' Simon to be welded up.

Unfortunately since I was marking up all the holes by holding the various pipes and parts in place, the hole in the AFM ended up being way off. Fortunately this was easy enough to fix by just rotating the AFM slightly, and I was able to use my old bracket by just flipping it around. I'm hoping to replace this bracket with something a bit nicer in the coming weeks.

The silicone joiners from trademe showed up and they look great. I think I may change the throttle inlet a little so I can use one on that also, just to make things look a bit prettier. I'm also thinking I might eventually replace most of the ugly black rubber coolant pipes with some nice silicone ones, although that isn't a financial priority right now.

I had to pick up some 30mm silicone hose for the plumb back pipe, it was only $15 from Alert Engineering, seem to be a bunch of good bastards out there too, which makes a nice change! I also picked up all the necessary hose clamps. These are called Breeze clamps, they have rivetted construction so they don't splay open when you tighten them, and they also have a liner to stop the slots from damaging the hose. I also sprayed the AFM silver, I haven't done the intercooler yet as I had run out of white paint.

So all that's left to do now is to get some vacuum line to make the BPV functional.