Generally speaking, an H-pipe is quieter than an X-pipe, larger pipes are quieter than smaller pipes (sound volume-wise, larger tubes have more 'deep' sounds that rattle and drone), and of course cats will smooth and quiet the exhaust.
You are correct though, that as the exhaust gasses move back from the engine, they cool and shrink in volume, meaning a smaller pipe can be used to carry the same volume of exhaust gas.
I have been following the same train of thought as the poster, BCM. I have heard tons of ponies over the years and have come to know almost all of the suptle differences between the various combinations of exhaust, for the Fox at least.
I have decided to go back to the stock 2.25 tailpipes, as I find those coupled to flowmasters (40's) are desired by my ears. Too quiet and it's just no more fun. Too much drone, and it's just no more fun. I think we all come to a place in our stang evolution where we get over the full out rumble sound and want to settle into a sound that is just below the sound of a "Street Race About to Happen."
BTW, I am still looking to buy a good set of stock 2.25" tailpipes for my 86GT. LMK what you have. Funny, everyone I know took them off their cars but no one seems to come online to sell them...????
I have decided to go back to the stock 2.25 tailpipes, as I find those coupled to flowmasters (40's) are desired by my ears. Too quiet and it's just no more fun. Too much drone, and it's just no more fun. I think we all come to a place in our stang evolution where we get over the full out rumble sound and want to settle into a sound that is just below the sound of a "Street Race About to Happen."
BTW, I am still looking to buy a good set of stock 2.25" tailpipes for my 86GT. LMK what you have. Funny, everyone I know took them off their cars but no one seems to come online to sell them...????
Brett, I'd go for reduction at the tailpipes just behind the mufflers if you have fairly new Muffs. If not, and you do not nor plan to build a mod motor, then start after the Cats. Most folks just thru on a set of mufflers anyway and didn't change the cats. That would put you back to stock dia.
The sound of drone is usually somewhat contained once a little back-pressure in induced at the tailpipes as the exhaust is recompressing going from 2.5 to 2,25 - kinda like a blow nozzle... Others, will want to straighten this idea out more clearly.
Where do you plan to get the TAILPIPES? I've been looking for an OEM set forever. No one have come thru for me with a nice set of take-offs. How about guys, who has a set of 2.25's laying around? Me and Brett are probably the only two Stangers that want to put 2.25" pipes back on; that mean ther should be about: 3 or 4 Hundred Thousand sets out there somewhere
Dude! They sound sweat! I have Flowmasters dumped in the same location and they sound like a Track-War about to break out. Those VT's are so much smoother.
That's the thing about Mustang exhaust, I want all of the sounds! I guess I'm just a Stang NUT.
Brett, it's not going to work.
When i bought my car it had 3 chamber flowmasters welded in stock catback and a stock h pipe. It was fairly quiet especially compared to everyone elses cars that were catless.
I found a 2.25 offroad h at the junkyard for $50 and installed it.
It was loud catless, and no different than when i put a real 3 chamber 2.5 inch catback on a few years later.
A 1/4 of an inch pipe size will make no change.
Either change the mufflers or add cats.