Comparing high performance regulators to budget regulators is difficult. I used to sell car stereo, and when someone asked why they should spend a thousand bucks on a new system when the factory unit sounded fine to them, I said don't. If what you have sounds fine to you, you would be wasting your money.

But when someone gets used to a high fidelity system, a factory unit just won't do.

The same goes with regs. I have a friend who has a G-250 and an R-190, and it doesn't matter to him one bit what he's breathing. I, on the other hand, once put an R-190 on an O2 bottle, and after breathing for about a minute, switched back to my backgas, doubling my deco time. I'd rather breathe a good reg for ten minutes than a piece of crap for five.

As far as comparing the Mark 5 to a 17 or a 25, it's going to be a half step below the 25, but better than the 17. A piston is going to give you higher flow. The ONLY reason to use the Mark 17 is if you're diving in freezing water or sewage. The reason the Mark 5/G-250 combo I mentioned is so good is that it's the older model G-250, not the G-250HP. Apeks? Not in the ballpark.

Caveranger, if you can't find kits you aren't looking very hard. Apply yourself!

Also, I believe all of those regs mentioned are made in France, not China. And nobody's going to buy a new reg and then tell you it doesn't breathe great. I don't think they're lying, they just have never owned a high performance regulator.

If something happened to all my regulators and I had to replace them all, what would I get? Either used stuff from the 1990s from Scubapro off eBay, or if I were buying new, Atomic Aquatics. They're the only thing that compares to the Scubapros