Curious question-regular 4-stroke vs pro xs 4-stroke

[Highcentered]

Sorry, don't have serial numbers for this general question. Let's assume all motors are brand new in the crate just delivered from Mercury. What's the difference between the regular 115 and 150 4-stroke and the pro xs model of the same hp? Just a hotter tune to give some bonus hp for that extra 1-2mph or what? Upgraded internals to hold up better being run near or at the limiter for extended amounts of time? I think I noticed a slightly different gearcase ratio. Would one be more reliable than the other over time?

[5keepers2]

I think the only difference between the regular 150 and Pro xs 150 is the lower gear ratio.

[dwtaylor]

Basically the pro-xs lineup of engines are designed for higher performance, regardless of horsepower or family. They are designed for better overall performance, speed included.

There are some slight component differences between the pro xs and standard in addition to some tuning to get the extra RPMs and a little more HP. I can't say with 100% certainty, but I heard that the pro xs are +10% of the rated hp and the standard are at the rated HP.

The gearcase on the 150 vs pro xs 150 are certainly different besides the gear ratio. The 150 pro xs gearcase is a derivative of the verado style gearcases so it is a little bigger.

[Coastal Mountaineer]

I understand the regular 150's can be 1-3 mph faster than the ProXS models on the same boat. However, supposedly, the Proxs's have better hole shots, mid-range acceleration, higher rpm's allow more prop choices, and slightly better fuel economy. As to reliability, mine has been flawless and I haven't noticed any posts here concerning engine problems.

[EuropeanAM]

I think the only difference between the regular 150 and Pro xs 150 is the lower gear ratio.

Not quite. Far too many engines and variables to make blanket comment, but in some cases (such as the 200) they're an entirely different displacement.

Some of the ProXS models also have different mount configurations/composition, as well as higher RPM range.