[@ADamnFiddle]
Did some research on Issei. Based on the Boosted Gear's function as a multiplier, I'd say Issei can enter any reality regardless of the limiter by limiting the amount of times he doubles his power. Furthermore, at max power, I would estimate him to be at skyscraper level, somewhat below city block level. He would be able to destroy a large building like a football stadion at max power in a single attack, and has speed and strength of similar scale.

If you disagree with this evaluation please inform me, and I will adjust my judgement.