i got headers for a gift. so i put it on and come to realize that the ports on the headers are smaller than the stock ones. i still put it on. im not sure if i feel a loss or gain of power. not even sure if they are smaller than what is on the head. i understand that if the heads are smaller than the one on the head then i would be losing power. is that normal??

i bought a head and port and polished it. my car has 155k miles. should i replace the timing belt and water pump? and what gaskets set am i looking for and where should i buy??