Changing tire diameter?

I was wondering if it would be a good idea to change my tire diameter to get better performance? Not sure which way to go tho. As my legacy l is under powered but also is geared to high and has too much acceleration to have any top speed. I plan on putting a small amount of boost to it soon. But was wondering if anyone has any experience with or has a recommendation or idea of whether i should go down in diameter and try and get as much acceleration as i can and how that would transfer to top end acceleration or if i should go up a bit in diameter and try and get a little more top speed. Or maybe i have that backwards?

smaller tires would make the car peppier i think, but suffer at higher speeds due to more rpms. bigger tires would help the higher speeds with less rpms, but lower your low rpm power to a point. i know that going to a +1 didnt change the feel much at all, but did lower my rpms at 70+ on the freeway. better gas mileage that way also.

It's not that big of a deal to change up diameter, width and tire compound. The cars are under powered no matter what, so if you are looking for it to be better at something specific like on/off road grip or wet/snow capabilities then why not. I run 205/55-16s with generic all seasons on them for daily driving and then I have a set of 215/45-17 with sticky street tires for fun summer driving. Just for reference my car came with 185/75-14s from the factory. Just keep in mind brake and wheel well clearances, and changes in the speedometer accuracy.