basically if you go for enhanced performance thrusters, you want to get your build as ligthweight as possible... at least below 90T, better below 80T, and if you can manage via engineering below 70T 
easy with a couier, doable with a eagle, hard with a viper.
for exampel my courier: https://coriolis.edcd.io/outfit/imp...yPKj9v/1ncaTZ+0C+/ALNQEvL/wEAAA==&bn=Sam Yoko
maximum speed increase is 160% compared to 116% with a class thrusters;
and maximum turn time decrease is 70% compared to 84% with a class thrusters.
easy with a couier, doable with a eagle, hard with a viper.
for exampel my courier: https://coriolis.edcd.io/outfit/imp...yPKj9v/1ncaTZ+0C+/ALNQEvL/wEAAA==&bn=Sam Yoko
maximum speed increase is 160% compared to 116% with a class thrusters;
and maximum turn time decrease is 70% compared to 84% with a class thrusters.