I don't know the numbers off-hand, but I don't have measuring equipment that can measure such a difference...
Just playing around with the oil control springs, it didn't feel any different to me...
...but I'm not a precision piece of measuring equipment.
Whatever the case, I burned through a set of the comp springs just as easily when I had an oil pressure problem.
Personally, I don't think it makes that much of a difference for most people unless we're talking about power figures that start to get close to 400hp...
I can't offer any experience with the side seal springs...
With that said, I have had zero problems running the stock, FC side seal springs.
In fact, I reuse most of those pieces unless it's obvious that they are worn past spec...
For oil control rings, if just the copper plating is worn off, I'd still reuse them; if there are signs the base spring steel has been worn, I throw those away.
Now, this brings up an interesting discussion...
All those parts increase pressure of the seals on the side housings.
For most of us, we're reusing good, used side housings...
This does not apply to brand new side housings, nor for those who can afford to re-coat (i.e. gas nitride, similar, or better) the side housings.
Since most of the original gas nitride surface treatment has been worn away, I've been seeing accelerated wear on them.
Rebuilds for under 400hp, I tend to stick with the stock stuff - with the exception of the FD corner seal springs (but even those tend to accelerate wear on the side housings too).
If you're looking for north of 400, there's a lot more money involved, and that usually gives you a lot more options.
Personally, for 300hp, I'd just reuse your original seals, if they are in good shape.
If you're paranoid, you're welcome to buy new (upgrade, i.e. FD) springs and / or the comp springs.
-Ted