Can you answer this question?

I've been lifting for about 15 years. I've always stuck to the basics, ate a high calorie diet and worked hard. I've tried many programs and most of them worked to some degree.

My problem is this. I've built up some impressive strength (425 bench, 475 deadlift at 6'1" 260) but I just don't get any bigger or fuller looking. I have a thick torso (chest and back) with wide clavicles, but would like to have more rounded delts, traps and arms. I really want to improve my appearance but am wondering if taking a "powerlifting" approach isn't giving me exactly what I want.

What to do? Up the reps? Slow the reps? Constant tension? Any advice is welcomed.

I think you may of ansewerd your own question.

Some measurements so you can have an idea.
Chest 50"
Neck 19"
Arms 17.5" flexed

You think the few things I mentioned may help add size? Like I said, I use some serious weights in the gym. Just the other day there were these two pumped-up college kids in the gym hitting the bench. They were working out with like 245, huffin and puffin and acting like bad asses. I was jealous. They had some pumped-ass arms, lookin real hard. I get on the bench and push 365x5 and I just don't look the part! Sucks.

You'd think a guy who uses 295 for close grips would have some 20" arms!

I've always done few sets, very heavy. Maybe 4-5 sets, 10-15 reps, squeeze the weight instead of lifting it? Are you guys in agreement?

Damn man..u can bench 425 I want some of that. I'm cutting down right now and I'm experimenting with some powerlifting. Im trying to get my bench, squat and deadlift as high as possible..I figure I have enough size. Maybe you know some tips with all that weight you're throwing around.

I've used many different approaches over the years. Heavy Duty worked for a long time for me. Once I started toying around with 315, I decided to see how far I could go and started using a Westside Barbell program...but tweaked a bit. I would train Frequently with low volume and varied intensities. A Speed day, a medium day (short of failure) and a heavy day (failure+ negatives, forced reps...). I was using this very recently and my strength was awesome.
But like I said, my arms are about 18" and I want them ****ers to be huge and to show all the hard work they've put in. I'm thinking of switching to more of a volume approach. Maybe adding exercises and sets to my existing routine.

Try changing up your workout a little. I try to change my routine about every 3-4 months. Not dramatic changes I'll change the speed on the positve and/or negative phase, change the number of sets or reps, change order in which you do them or do forced reps. Just see what works for you. I'm usally really sore for the first few weeks after I change my routine.