During my last couple of years in high school, my best friend had an older brother who had 3 little aluminum boats and a cabin at Lake Texoma, so we spent a lot of time up there and frequently camped on the islands in the lake. The older brother was a mechanic and had 3 Mercury outboards, all of which had stickers showing considerably less horsepower than the original stickers. I can't remember for sure, but I think they were 25 hp with 15 hp stickers. There were no limits on the lake; he just did it so he could sucker people into races.
However, one of my brothers bought his 17' Lowes boat in Alaska with a 45 hp Johnson, but the dealer put a sticker on it that showed "Alaskan 35" because 35 hp was the limit on the Russian River where my brother wanted to fish and it was legal to do that because, in addition to the sticker, the dealer replaced a piece of the throttle linkage with a shorter piece so the throttle couldn't be opened all the way. Of course he gave my brother the original linkage, too, and it was a simple matter to snap one out and the other in, so we had full power when we fished Hidden Lake and Resurrection Bay, and also lakes in Texas and along the Texas coast after he moved back down here. You just didn't want to get caught on the Russian River in Alaska with the wrong linkage under the cowling.