Well you could, I don't think 2 cylinders in one pipe would run all that well. Subies have two collectors join into a straight pipe as its a boxer configuration, but they join back up into one pipe not too far down the exhaust path.

A true dual would create less backpressure yes if you sized the piping the same for the single and dual. Hardly any cars run true duals because most cars don't run that well with them... as most V8s are n/a and therefore require some measure of backpressure to keep some low-end...Most V8s have an H pipe (a piece of pipe that joins between the two separate exhaust paths) to help scavenge. Some amount of piping is necessary in all exhaust setups, even turboed ones, hence backpressure will always be present.

 

i got another idea b4 you paint it ( if it's not ) just put carbon fiber filler in that second hole sand it all nice and stuff make it cute and go with one pipe IMHO

 

Or you could just do what people have done for years... weld a piece of pipe and matching exhaust tip in there. I worked with a guy this summer who's like 60 and used to mod GTO's and all those great classic muscle cars, and he was telling me that he did that to his GTO back in the day, so it's nothing new...

 

rice^^!!

fill the hole in, no reason to go dual on a 4cyl, but if done right you can do it so you won't lose any power, not really worth the hassle imo.

 

What makes it rice zoned? It's a lot less work then filling it, and if he likes the dual look, which I do as well, then it looks better. Who cares if it's non-functional?

 

You answered your own question...its not functional.
Plus, over time, it will look like shit..this is because the real one will start to discolor or get a little black soot in it from actually being used, and the dummy one will still look shiney and new.
plus buying another muffler that is the exact same as the one you have is going to cost just as much as a little filler+paint, since the kit has to be fitted and painted anyway.

 

Non functional parts, on ANY car, is RICE. Sorry, it's just a fact. Wow, I like the way 2 exhausts look, THEN HOOK IT THE HELL UP. Enjoy the loss in performance, as you'll get it even if you don't hook it up. Heavy ass muffler, bodywork that'll crack after some decent bumps.

4 Cylinders don't need dual exhaust.