You can't use the Y-section from your Stillen kit without modifying the MAF housings. It is designed to "pull though", (when on the S/C intake) and by flipping it round (in your engine bay) you are trying to "push" the air in the other direction.
The only way you can get it to work is by re-drilling new holes in the MAF sensor housing to have them mounted 180 degrees to what they are now.
Also, since the Y-pipe is only 2.5", you will run out of resolution on your MAF sensors in no time.
When EVOHUNTER comes back in the spring, I'll have this system working perfectly...pushing this kit to the limit, or as far as the belts hold
.