Does it really help in hp, also I have a 2012 lancer es with injen cai, if I cut the exhaust and cat off and just run straight pipes will this make the car faster?

 

Yes, if run the straight pipes it will make the car incrementally faster. However, you could be accused of being a douche. Don't give Lancers a bad rep.

Don't do it.
ever.

Spend the money for a good exhaust. If you don't have the money, then wait and save.

 

What type of exhaust do you recommend?

 

That would be better answered by other ES/GTS/GT owners.

I'm not sure my 'modified OEM muffler' trick works for ES/GTS/GT...

Consider first getting a high flow cat (or test pipe) for best $/performance improvement. THEN search for a catback exhaust. I say this because too many people buy the 'loudest' exhaust and THEN remove the cat and it is unbearable. They sell it and then buy a 'quieter exhaust' so the combination does not drone.

It is always best to have a goal, budget, and then a plan for the car. This saves money and time on mods that may not complement each other.
Good luck!