I had to cut mine to get everything in. I had the DSP on the very bottom and the HVAC just above it. IMHO, I did a poor trimming job and think that others could give you better direction in how to and how much to trim.
Also, because of where I put the HVAC I had to cut the bottom off of a trim piece to make it fit. This may be because I had a DSP in there too.
If you want, I'll ship my old one to you.