Originally Posted By: Hokiefyd
The original claimed reasons usually revolved around getting the exhaust manifold as close to the catalytic converter as possible, for quicker light-off after a cold start. Putting the exhaust at the rear of the engine better facilitated that. I personally prefer this layout, as the exhaust manifold typically requires little-to-no servicing during the life of the vehicle, and it's packed away in the rear where it's out of the way. The intake manifold, however, sometimes has butterflies that may need servicing or PCV or breather valves that sometimes need servicing, and it makes sense to have these in the front of the engine.
Now that exhaust manifolds are commonly integrated into the cylinder head, and catalytic converters are smaller and bolted straight to what is essentially an enlarged cylinder head, it's more common to see the exhaust on the radiator side of a transverse engine. I still don't like that.
Related anecdote: My 2011 Camry's AR-series engine had the exhaust on the radiator side and the intake on the firewall side. Guess how long it takes to replace the PCV valve on that engine. It's a 4-6 hour job (by the book) and requires complete removal of the entire intake system. There may be noise benefits to putting the exhaust at the front. Not worth it to me, though.
Wow, thats a pain. I was able to replace my PCV in about 5 minutes.