This mod is pretty simple, you basically install it as a normal mod and you need to level up at least the first card of the perk deck.
Once you have done it and the perk deck is equiped you will get enough exp with a Jewerly store at normal with the -30% malus to get 100 levels (even more but 100 is the max)

I merged two mods together from two other guys, links just below

GAB's site: https://www.payday2.pw/ (here there are A LOT of mods for payday 2, I used XP Increaser to get the xp bonus effect)

LE_BarnOwl mod: https://modworkshop.net/mod/29390 (I used this mod as base)

I recommend using this mod only if you are good at the game, learn to play and then farm like crazy, trust me, it's worth it.
Overkill released 500 after 7 years. Hundreds if not thousands of people were 25-100 for years and they have pretty much mastered the game, grinding another 475 infamies for
Pretty much nothing (wow, weapon colors, sounds when you enter lobbies, outfits, gloves...) it's not worth like 2000 hours. I mean, if you are infamy 500 you would expect 
AT LEAST to destroy the game but Overkill didn't give us this, they didn't give exp boost either (At infamy 25 and Infamy 500 you have 205% exp boost so...).

I hope you find it useful and even if this could be counted as cheating I think is a cheat almost acceptable.