So I'm interested in installing an ebay FMIC, specifically a CXRacing kit and am thinking about the 28"x5.5"x2.5" core (2" in/outlet) with 2" piping. I've read all about ideal setups using the 2.5" piping and even 2" hot pipe and 2.5" cold. However, I don't see the reasoning of changing the size for the cold pipe; if, by chance, there was a noticeable amount of change in volume for cold air considering it's denser, wouldn't it have less volume? It's becoming more compact. I'm imagining a 2" setup would not only work with the T25 2" compressor outlet, but be more efficient since there would be more pressure in the pipes compared to 2.5" allowing for quicker spool/peppier throttle response. My only question is the effect it would have, if any, on joining the pipes with the 2.75" MAF with that drastic of a silicone reducer. I think any flow impact would be negligible. Lastly, is there a reason there seem to be no universal 2" pipes with a BOV flange, SSQV or type S? Is it not safe to weld a flange on this size of pipe? The smallest I've seen is 2.25" from CXRacing.