Ribbon Delete (remove the spark arrestor). Several threads on here about how to do it, and what the risks are.
Clean the air filter.
Make sure oil isn't overfilled.
L13 Cone can help with pump efficiency.
Seal the intake tunnel (same reason)
All of those won't really help performance from a top speed standpoint, however they will help your boat be more consistent across different loading conditions. The only real way to get better performance is to repitch the impeller and get MapTunerX to reflash the ECU's and increase rev limit.
@swatski did a TON of research on this in his SX190. Managed to get near 50mph with the bimini stowed and just him in the boat. He found that the stock impeller was the best all around solution, and that the added revs and timing of the MapTuner helped pick up a few mph in normal conditions. He was still only in the mid 40's if I remember right.
L13 Cone and tunnel sealing will get rid of cavitation (if you have any). You'll know right away if you do. From a dead stop if you go WOT quickly, do you hit the rev limiter? If so, you need to seal the tunnel and consider an upgraded pump cone. If not, that isn't your issue.
IMO 42-45mph in a FSH190 is an aggressive expectation from a stock boat. I've got a shade over 240hrs on my AR190 and have only seen 42 a handful of times in the last 7 seasons. More often I'm closer to 39-40mph at WOT, and usually cruise in the 30mph range around 7k rpm. Thread linked above seems to support that. Keep in mind heat and humidity kill the air quality for a normally aspirated engine. Goes double for one locked in a fiberglass box. I see consistently faster speeds and noticeably more power in the spring and fall. It was noticeably down on power when we were in Destin 2 summers ago. Was 95 deg and about 700% humidity while we were out. Came home the next weekend and took it out in 75deg overcast weather and got 2mph more from it.
Bow weight will absolutely KILL the speed on a 190. The trolling motor on the front, and the batteries up front are killing your speed in general. I can drop 4-5mph by moving 2 adults to the bow from the stern and changing nothing else. The boat isn't long enough or heavy enough to keep the jet angle pointed in line with the direction of travel when the bow gets heavy. Trim would be nice in this instance, but the already somewhat weak nature of the engine/pump combo might waste more energy in redirecting the thrust than the benefit of using it would yield. Not sure anyone has tested that though.
Check your revs. If the needle says 7,800, you're likely getting closer to 7,600 or so. Tach needle on mine doesn't match the digital output, not a big deal, but something to be aware of. I think the rev limiter is 7,750 but I'm fuzzy on that detail.
Had 3 adults and 4 kids in our '17 AR190 on Sunday. We got a top speed of 38mph @ 7,550 rpm. Fastest I've ever seen this boat is 42mph on a cool fall morning at near sea level, and I've owned it since new.
