I'm not sure if any of the exhaust designs provide any noticeable power without ECU programming.

BTW, i've decided to go for the pulleys. I'll order it some time next month. There are more than 15 people on the TSX forums and many other who have installed it on their RSXs without any issues. I think it's a safe enough mod to do. I'm also thinking of installing a new battery and possibly a volt meter in the future just in case.

Will keep you guys updated!