I don't post often but after reading this thread I had some thoughts. OH NO!
1: When running jet limited classes you look to improve the flow path as much as possible so twists, turns and other restrictions don't hinder the jet itself. One way of doing that is to use the biggest noid allowed on the nitrous side.
If you don't have a rule against it the Combo-Flo air mini noid fits the bill due to it's design.
Std electric noids have the nitrous flow nitrous going in, turning up, turning left, turning left again to go out the noid. All these turns hinder flow. It's hydraulics 101 stuff and any basic flow testing confirms it. The mini airnoid design is what I call a High Port. Kind of like a great cylinder head design. The inlet is a direct line of sight to the orifice. Nitrous or fuel goes in, makes 1 turn and goes out. That's where the giant flow numbers on these things comes from in addition to the large orifice size and piston lift.
2: As John Heard knows the -4 line is a cork. Short is better. Also shop around for the hose that has the largest Crimped inside diameter. They do vary depending on the manufacturer. Buy a short hose from each to find out. Check with your local hydraulics hose guy also.
3: Flowing a system, is a huge time consuming, non profit job. I hate doing it. When someone actually does it you should wince hard at the cost, then pay it. If you don't wince the chances are it's not actually being done on that particular system. If you spent 600 bucks on a plate deal, there should be another 1000 bucks worth of time flowing it...and that's still not a money maker. It usually winds up being less than minimum wage per hour. Would people buy enough of them for the seller to make a living? Probably not since magazine articles lead everyone to think they can rotate the earth and be World Champion for less than 500 bucks....on the first day.
In all fairness when an independent nitrous shop works with the same mfg jet and plate all the time the chances are very good that they will all flow "within a +/- range". Hence the reason you usually get numbers on a paper that look just like your neighbors flowed system. Is it a rip? Not really. The word flowed is being used rather loosely though. Like some mfg that sell shiney "flowed" jets for 3 bucks. Come on now. That only occurred on the first Beta jets, if at all.
In the end look at the price. It was affordable, even cheap, for the HP potential promised was it not? The seller has done the leg work and knows what range it is in. Since every engine is different in what tune it likes you still have to tune it anyway. It is also important to remember that you are not just buying parts. The parts are nothing. You are really buying knowledge which is priceless.
4: As a result of nitrous "flowing" being a non profit center and when
Nitrous Master came about I tried to put as much info as possible in the help files on how to do this yourself. It's not rocket science. Well, maybe it is since the model rocket guys use nitrous as a propellant. In fact I am currently rewriting that section and adding some pictures. Should be about a month before the update.
5: If it were me I would buy several .073 jets that pass whatever test the rules dictate. Then sit down and flow them to find the one that not only flows the most but is the smoothest flowing of the bunch. By that I mean it's mostly a visual thing if you don't log it. Some shoot to the left, some right, some straight down the middle and some swirl funny. Water at 10 lbs or more works best for this visual test.
6: I think it's good that the actual nitrous user/tuner understands how things work. The payoff can be both personally and financially satisfying when "it works as expected" and/or you come home with your stuff in one piece.
Doing your own flowing helps you find the limits of your system and Makes my life easier. Once you get into it you will start looking at a lot of different things in your system to make it better or more efficient. It can be a fun learning experience but it does take considerable time. Good winter project the first time around.
7: If I were king and was limited to an .073 I might want to try a plate tube with a ID smaller than normal to keep the velocity up. What size? Don't know. Just thought about it from time to time. Just threw that out there to make you crazy and get you to thinking.
8: Current Perimeter plates have all been a disappointment to me. I haven't seen one yet other than the original NOS plate from the 90s (no longer made) that flows somewhat evenly around the thing. Run some water through one to see what I mean. It's a pretty substantial variation. Other than that the concept, function and end result is far superior to bar plates.
9: Flowing Mechanical Fuel injection. Now, this is not a DIY project and is a totally different animal than a steady state nitrous system. Flowing MFI is a must to save mucho track time. Every one of these supposedly identical systems is "like a box of chocolates" and have their own vastly different personalities due to pump efficiency, line lengths, nozzles, yada, yada. Just thought I would throw that in.
John, If this bordered on an advertisement just delete it.