I tried a search but could not find the correct words to find what I was after.

On the upper IC pipe, going from the turbo to the IC over the top of the engine, in the middle the is a reducer - actually, it should an increaser as it appears to increase the diameter of the piping from about 2" to 2.5" or something like that. What is the proper name of that part?

I'm puzzled as to why it is there - what is the function of it and why was the middle of the pipe chosen rather than right at the turbo outlet (I think most turbo setups do it at that spot) or keeping the smaller diameter piping going all the way into the IC (then having the larger diameter leave the other end of the IC).

In theory, bigger piping would decrease the pressure of the same amount of air and also slow down it's flow speed. But I can't figure out why it was placed in the middle of the pipe as opposed to one of the ends - what is the advantage of having it in the middle? It seems to create an extra spot for a pressure drop before it gets to the IC or something...

 

Well, smaller piping does increase velocity, but larger diameter increases volume. Why mitsubishi chose to do it the way that they did is beyond me, but the fact is that it's a restriciton. Every test I've seen, as well as my own dyno tuning results, have shown that upgrading the UICP with one that is a constant diameter of 2.5 all the way from turbo to intercooler produces 10-15 whp gains with no loss in spool whatsoever. It's one of the best and most surprising bang for the buck mods you can do to your X. I highly recommend the Nisei 1 piece in matte black. It's fairly priced, and is the best piece on the market IMO. Hope this helps.

 

yeah actually it was a same in the previous versions. Just a difference is now the UICP is a same as was earlier the LICP. Just remember how good mod was the LICP before.