Here is an exhaust system combination I bet you haven't seen yet. This system consists of 2 Jones Turbopack mufflers (these are 2-tube mini-turbo mufflers contained in a round case that looks like a glasspack). The largest one is 5" diameter by 24" long case. The inlet size is available in either a 3" blank (which is what I bought, it's also the cheaper of the two) or 3" tube connection. The 5 x 24" turbopacks with 3" blank inlets p/n is JONATT5024B available from Full Line Exhaust:
http://www.fle-online.com/InformationPages/infoturbopacks.htm
http://www.fle-online.com/OtherProducts/OTHGlasspacks/turbopacks.htm
These have two 2.25" dia perforated tubes inside them, and the thickness of the aluminized case is 15 gage and the welds are quite beefy. These mufflers are built! I bought 2 of these to put under the floor of my '75 280z, (did have to beat the right side of the tunnel in a bit for clearance), Forget about using these in a 240, they won't fit, but you could try the smaller 4" dia ones. Now orginally I had a Magnaflow 4x9x14" Dual in/Dual out muffler (p/n CARS11386
http://www.fle-online.com/MAGNAFLOW/MAGUniversalMufflers/alu4x9.htm) in back in the original mounting spot, since the dual 4x30" glasspacks I had under the tunnel were too loud for me by themselves. I decided to keep the Magna in addition to the two new Jones mufflers for maximum quiet.
Notice that I used a piece of the old 4" glasspack case on each end to adapt from my 2 1/2" pipes to the 3" case on the Jones mufflers.
It now sounds quieter than it did with the old glasspacks, but you can still hear there's a beast under the hood, about 1/2 of the low-frequency rumble is still there, but now it has a cool metallicy pinging sound, like the sound of the individual firings going into the header pipes are being amplified a bit by the Jones mufflers. With the Magna adding a bit of a european sting to the tailpipe, the overall effect is quite cool, fairly quiet, and alot different than some old Mustang with dual turbos.
PICS: