I own an NW-200, and I modified my pump, and it is now an absolute beast. I'd put up against most $500-$600 skimmers any day.
A kill a watt is a good thing to have before doing this mod, to make sure you don't overwork the pump. To modify the needle wheel, you need to take a knife and pry off the top needlewheel. There are two needle wheels when you look at it. Do this very slowly and pry softly/evenly around/between the two nw's. Once you pry the top nw off, cut three layers of enkamat roughly a bit larger then the actual size of the stock NW(you will trim them down later so they don't rub. I used three layers of enkamat on mine. Skip the zip ties, they weigh too much and can distort the balance of the wheel. Use fishing line(8 or 10lb test), and tie the enkamat to the remaining needlewheel. I used a needle to thread the fishing line around the stock nw and the enkamat. Be very redundant and keep taking the fishing line around the nw and enkamat to make sure all parts of the enkamat are secured to the remaining stock nw. This will take a bit of time, but once you've done this right, you won't have to worry about future failure. After the enkamat is safely secured, trim the excess edges of enkamat so it is the same size as the remaining stock needlewheel. You don't want any rubbing between the enkamat and volute.
I then went to Home Depot and bought a water connecter(male to male) at 1/4' to make a larger venturi. This allows the pump to such more air. Drill right above the stock venturi to put this connector in. You must cut the end of the connector at a 45' angle and once you put it in, make sure the smaller size if facing the impeller. This allows the pump to pull the air easier. Then you just can buy 1/4' tubing to attach to the end of the connector to pull. Now your venturi is not as restricted and the pump can pull in more air.
The last mod is to use a dremel to shave out the top of the volute, as well as the 90' elbow that goes to the actual skimmer. The 90' is too retrictive and doesn't all for enough air stock. Shave it slowly to enlarge.
If you do all three mods, the skimmer should pull about 3 times as much air as it did stock.
I probably made it sound more complex than it is, but this should help out.
Google: Octo NW200 Step by Step to 40scfh
