I have a 95 Sentra XE and my engine has been getting louder and louder but rides like brand new. i think i have vacum leaks but dont know where to start on getting rid of those. My engine light keeps coming off and on with no ride difference. i got the code read off once but all they said was exhaust system. What could that be? and i have plans on installing pace setter headers and cat back exhaust and injen air intake are they easy to install or should it go to a shop?