405 when you started working out? Or when you started 5/3/1?
Either way I assume raw? You have some awesome genetics.
15lbs in 4 months is not fantastic results IMO, but not bad either.
I have been doing a modified setup now that I am training raw. A really strong raw guy helped me set it up.
Basically, speed work first, then work up to a max. Either max single, double, triple, or even 5 rep max sometimes.
I do 6-8 triples with 50% with bands/chains, or 60% straight weight, then work up in singles after that till I am close to my goal for the day, then I will try however many reps my max for the day is for.
For example with a 420 PR, you could try the following:
Going for 1 rep max
210+ doubled monster mini bands for 6 triples
225x1 straight weight
410 or 415x1
And so on.
Then assistance work for triceps/back
The important thing to realize is you will not be fresh so do not expect alltime PRs all the time. You don't have to go till you miss either. Just go till it is very difficult.
Then another day do some light upper accessory work, and thats it.
I have really liked this so far.
Another plan that may be more suitable for only training one year may be WS4SB.. Still westside, but with more rep work, in place of speed. Although I would throw in a 3 week wave of speedwork every other month or so. My bench sucks ass though... if I am lucky I will get 400 raw by the end of summer. The above is the first thing to get my raw bench moving significantly in about 6 months though. In about 6 weeks I gained more training like that than I did over the past year on my raw bench.