Hi I am looking at putting a different muffler on my 93 Q45 and was curious. I know I am not going to gain any performance, but I am just looking for a little more tone.

There are two pipes on the car that flow through the muffler, but all the mufflers I am looking at have one inlet. If I reduce it from two to one inlet will that mess up the performance negatively?

It shouldn't, provided you don't bottle neck both those pipes down to 1 pipe of the same diameter... you should use it sort of like a collector and then increase the diameter of the 1 pipe.
Example - if you have 2 2" pipes going into the current muffler, and have to reduce down to 1 pipe, you should reduce down to one 2.5" pipe or something.

If you go down to 2.5", you'll be reducing your flow area from ~6.3 square inches to 4.9.
If you go down to 2.75, you'll be reducing the flow area to 5.9 square inches. just try to keep that reduced area as short as possible.

nonsense......there are plenty of dual inlet to dual outlet mufflers out there....get the correct setup instead of ghettoizing it.

Trust me I don't ghettoize any of my cars... I have an RX-7 and an 05 Accord too neither are ghetto.

Thanks for the advice, I will keep that in mind papasmurf!

are you sure your Q isn't running on 22's with candy apple red paint job and hittin that 3 wheel motion with a licence plate saying "GHETTO VET"?

haha I'm just kidding.

I deleted the rear mufflers and only run the middle ones. Thing sounds beast. I can provide a sound clip once I get it running again haha

Ditto on branscoset's suggestion. Several members have been happy with simply deleting the "suitcase" resonator at the back of the car. There is enough other stuff in the system to keep it from sounding like you're running straight pipes.