DLD, I used pumping to help straighten out my penis after the first onset of Peyronies. Let me give you some of my experiences, they might or might not help. First, I had the goal of straightening not girth. Thus when I ordered my first tube it was too big. It didn't do what I wanted. So I ordered a smaller tube and that was just the right thing. The smaller one, made my penis straighten where the larger, while it fluffed up and made it bigger, didn't give it the tug/pull I wanted.
Besides, the bigger one pulled in my nuts and I didn't want that.
Also, and this is very, very important, the pump will give you foreskin. If you pull and increase the vaccum it will give you a donut on the end of your schlong under the cornona ridge and that will increase the foreskin. I have a completely restored foreskin as a restult. I was impatient and wanted to get pumped bigger so increased the pressure to way more than reccomended. They say not more than 4 or 5 pounds vaccuum.
Also, a good vaccum pump at a parts house is much cheaper than you can get at some of the places like kaplan or Newart. Newart was the best for me for a tube. They were easy to deal with and helped me get right. I also liked their tube as it has a round ridge at the point it butts up against the pelvic area.
I pumped about 20 minutes at a pop and would shake it out and jelq a bit then put it back in and pump some more. You can get a huge pecker in girth!!! Then, I would let it stay that way for as long as it would. Sometimes an hour or so.
I think I gained more girth from the erect jelqs than the pump. I also think that clamping gives you more girth than the pumping but pumping is fun for a different stroke.
When you take you time and work a couple hours and pack a tube it is really a "high."
GS