Anything as simple as an intake or muffler delete will only be negated by the engine control computer. That will attempt to return the parameters of the engine to as close to factory as possible. I’ve modified a Corvette before, but it involved a lot of tuning of the computer’s map. I also installed a supercharger , heads, cam, fuel pump, etc. This will totally void warranty. That effort will give you real gains, which on a ‘Vette are reasonable. On a minivan? Not so much. Also, all the money spent on modifications will not increase the value of your vehicle, only make it harder to sell. This is well known among the sports car community.