You don't absolutely need the lower pipe, although it's nice to have. I am just using a solid UPP w/HKS flange from AGP. I have a GT40 turbo, by the way.
The UPP from AGP is new. I don't even know if it's for sale to the general public yet. It's worth waiting for. It actually has a screwed in, sealed air sensor. Fuck that grommet/plug BS...it leaks or just falls out with real boost. This new piece is really nice...no holes for anything, just a single built-in sensor. I wouldn't buy anything else.