Nope. Just note that antennas don't increase speed, it just helps get signals, meaning stability. Kumbaga side effect ang bibilis. Syempre if mahina signal mo mabagal ang internet, but if you are getting consistent signal then likely yan na ang speed mo talaga. If may change man, negligible yan, maybe a few mbps or so, but posibleng mas maging stable ang connection/ping mo. Ang magiging hindrance lang naman if nasa gitna ang modem/router mo ng bahay is pader and other houses na kelangan tagusan ng signal (lalo pa sa Pinas e uso ang hollowblocks instead of boards like sa US), but if nasa may window ang modem and router mo and you are getting consistent speed as you mentioned above, maari lang aangat ang speed mo ng onti and maybe an increase in stability or ping. If ok ka dun, go bili ng mimo, if iniisip mo na dodoble ang speed mo despite already getting 8-15mbps (which is already good for the Philippines when most are barely getting 3 to 5mbps) e malabo yun tol. Kung akala mo MiMo will turn your 15mbps to 30 or 50, no. Ang kalaban mo na lang is congestion sa area mo. Ang gawin mo instead of buying mimo or sims, check what network gives you better speed and connection (globe, smart), stick with that and configure the settings na lang. Specifically find the best band and tower na hindi congested using tower finding apps (forgot the name of the app, basta hanap ka YT/YøùTùbé cell id locking and band change). If di ka satisfied sa changes na gagawin mo then go and buy an antenna and see if that helps, but I'd suggest go with the free option muna or cheaper option and see if satisfied ka. If not then buy the antenna (mahal kasi ang legit na antenna, around 3 to 5k usually).