I just started this and want to share in case others are stuck like me. I've been stuck at a 1rm of 215 so I looked this up because I've heard great things.
Add 50 lbs to your bench
http://www.timinvermont.com/fitness/benchpgm.htm
Check it out. I think it's worth giving a shot. I just did workout two and actually woke up sore from my chest... Something I hadn't felt in a long time. I think the inclusion of negative sets is huge and will help promote growth in ways conventional lifting won't.
Make sure you grab the appropriate spreadsheet for your 1rm and print it out. Try to follow as strictly as possible. I've seen a lot of guys report gaining anywhere from 20-50 lbs. Most hover around the 35 lb range, which for me would be amazing.
For reference, I'm at 6'2" 200lbs and I've been following GSLP.