I Kelly Blue Booked the 2006 Corolla LE I have, and it is listed at $10,625 trade-in and $12,815 private party. It has 36,000 miles on it.Adding a $600 suspension system. what would that do to the value of the car? Would I see any of it in the resale value?
Too slow? Mine goes 80 all day long with no problems. I think it has more safety features but that may not be important to you. Reliability is about the same but I think the Toyota has the edge (check Consumer Reports). You will need quite a bit to make up the difference in value; they'll be suspicious as to why you are getting rid of it and, if it is evident you have car fever expect a low trade-in value. Dealers are not likely to make any trade that doesn't put cash in their pockets. Will you lose the low interest rate that Toyota was offering a while back? Find a private party on Craigslist that wants to sell or trade their Nissan and will take over your payments. The other option is to wait it out and save up for another car in a year or so; you'll live.
Dealers don't care about such add-ons. In fact, they may look at it as a modification that they can not warranty. Some buyers will wonder if the car was abused and had to have the suspension replaced and be skeptical. You have to find someone with the same mindset as yourself to ensure that they see the value - or any value - in what was done to the car.
If you're replacing the current stock system with another factory system, any money you put in will not be seen back. If you're upgrading the system to some different (sportier) system, you'll only get something back if the next buyer sees any value in that new system. This Corolla is not the typical car to get a sportier system. Most of it's potential buyer would not be looking for this upgrade on it and not be willing to pay anything additional for it.
Borla, Magnaflow, or Cherrybomb aka Glasspack
Unless he is looking for racing, you shouldn't really consider HP gains into exhaust, as the difference will be basically negligible. You want to look at sound, especially for a 4 cylinder engine like that. In a 4cyl, high HP exhausts often sound like lawnmowers for minimal HP gains. Check out Youtube and listen to clips of different exhaust brands until you find one you like, usually the deeper the better Also, you will be looking at pipes, mufflers and headers. You can sometimes get them all-in-one, or you can pick and choose different brands for each