Hello, I have with me a 2019 Honda Civic Lx coupe with a mileage of 30,365. I bought her thinking I had a modified exhaust, later on I discover by accident that it was a welded straight pipe job. I hear that will be a problem for emissions later on. Also I would like to know if this exhaust I have will affect the lifespan of my car in the long run because I plan on keeping her for a long time.
If you are saying a straight pipe, I am assuming you have no cat. Depending on your state that is an instant fail. Removing it could have an effect on the cars computer system as parts are missing.
Well it really depends. If its an engine back exhaust and they deleted the CAT then you will have problems with emissions. If they just did a CATback straight pipe then you shouldn't have any issues unless it's tripping a code or something. You can easily tell by smelling your exhaust. If it stinks like burning gas then it's likely a engine back if it doesn't and smells like a normal car then its likely not but I would double check just in case because with a custom exhaust you never know unless you open the hood and check. CAT usually look like this 
Besides that as long as you like how it sounds and everything there's no major differences between a normal exhaust and a aftermarket or custom one besides getting extra flow which will help your car run better and likely help it last a bit longer since normal exhausts and very restrictive you can imagine it like trying to breathe out of straw... A factory exhaust is like a tiny coffee straw and yours is like one of those fat straws that you drink a smoothie with or a milkshake.
If it is straight piped and does not have a catalytic converter then that is illegal. If the police were to ever somehow notice that you can actually get a ticket.
