[HiFlow5 0]

Unfortunately, many people assume that higher octane fuel is better for all engines, no matter what. This is absolutely false. Ultimately, the best octane for any vehicle is the lowest one you can run without detonation (pinging) occuring. It's not the fuel that increases the performance, it's the fact that the timing has been advanced. The higher octane permits this to happen. In your case 87 should be just fine.

Octane, for all intents and purposes, is used to slow down, or control the burn rate. Modifications that increase performance, such as increased compression, or advanced ignition timing, will cause the mixture to become too unstable, and pre-ignition (aka: detonation, pinging) will occur. This is when the mixture fires on it's own, at the wrong time. Severe damage will occur if left untreated.

People often think of high octane fuel as being more flammable, and easier to explode, whereas that is actually the opposite of the truth. 93 octane will be tougher to ignite than 87 octane. Because of that fact, 87 octane will burn quicker, and 93 octane will burn slower. That's why you feel sluggish with higher octane.