Hydra, I'm not sure if you've attempted to trim your t-visor yet, but here's some tips I can pass along that I learned from cutting 3 visors...
1. Tape off the area on your visor that you will be cutting ( I recommend taping both sides ), green painters tape works great for this as it'll be easy to remove later and won't leave any marks or residue.
2. Mark where you need to cut/trim. Then double check your measurements. I like to make a cardboard template, which serves as both a template for fitting and for your mounting method. ( I went the chicago screw/bolt on way, so this ensures that your bolts and holes will line up perfectly.
)
3. Use one of the fiberglass reinforced cut off disks for your dremel tool. bring your dremel up to about 3000rpms ( provided you have a speed adjustment knob, if not... just wing it. ), and slowly go over your lines lightly scoring them. Go over the lines with multiple passes, this will help to prevent excessive heat build up in your cutting disk, thus reducing the amount of plastic "goop" the might cling to your disk.
4. Take your time. Go slowly and try to keep your hand movements as steady and smooth as you can.
5. Swap your cutting disk for a sanding drum, the 220 grit will do fine as this is to clean up and smooth out the edges.
6. Once you're satisfied with the newly trimmed visor, test fit it. If all looks good, then you can remove the tape.
Hope this will help you and happy cutting!