I can't see a y pipe will make any difference to the power on a standard tune because it is a forced air induction set up with more than enough air being supplied. Sure you will get some power gains from removing the main cat but even that isn't a gamechanger. I deleted the cat for the better and louder exhaust note.
It is like the gas flowed head work JUBU offer which is pointless on a standard car but works well with a larger supercharger or turbo conversion.
On a separate note I watched the YouTube video showing the best 5 Emira exhaust systems and it was a pointless exercise because they weren't all fitted with equal parts. Any of the systems would be better with a cat delete and even better with headers. To do a real comparison they need to be in the same setting (indoors/outdoors/going through a tunnel) and equal set-up. That doesn't even take into account what the sound was recorded on and where in relation to the exhausts.
The Emira exhaust being mid-engine is so short it is hard to make any big difference in design and the reason all of the aftermarket exhausts look nearly the same.
