Any idea how much lounder/quiter the car would get when changing from a RX7 Store resonated mid pipe to one of those metal high flow cats?

 

I have a gotham racing high flow cat that i would like to trade for a resonated mid pipe. If you decide to switch let me know.
Austin

 

Search button is your friend


https://www.rx7club.com/search.php?searchid=672858

 

The cat will be louder.

The metallic cats are very small, so you may be able to get one welded into your resonated midpipe without eliminating the muffler. That way you can avoid smelly exhaust and extreme loudness. I got my Random metallic high flow cat from Martel Brothers today (you can also get a Dynatech metal cat from Summit or Jeg's) and it is nice and compact. The center part is 6" long. The diameter is 4" OD. It is 9.5" long from end to end. The inlet is 3" ID, and the outlet is 3" OD. It weighs 3.2 lbs. The welds are smooth and it is shiny (obviously polished, but there are some scratches and marks from the manufacturing process that are still visible). Based on the fact that it is polished, I am pretty sure it is 304SS.

-Max

 

I just had the high flow cat put on to replace the stock midpipe. I haven't gotten the car back yet. How much louder do you think it will be than stock? I was happy with the volume with the RSR Dual Tip exhaust. I really don't want the car much louder than that. :\

-Joseph

 

The stock cat is pretty quiet, but the high flow units don't seem to do much muffling. It is hard to describe how much louder it will be even if I did know, though (which I don't).

Maybe we can get RX Tuner magazine to do a shoot-out of some popular cat-back and midpipe (straight, cat, muffler) options with dyno, flow test (perhaps more objective than dyno because of tuning -- maybe we could use a leaf blower like the turbo minivan guy did ), and sound level results. I would expect that it would be possible to round up some people to lend their exhaust parts for the test. Hell, we could probably do this kind of thing locally without the dyno tests for cheap. Have a BBQ, do some leaf-blower tests, use a single test car for idle, WOT in-car and fly-by, and in-car highway cruise sound level tests with a $25 Radio Shack meter. It might be hard to get decent sound level test repeatabilty in a densely populated area, and the leaf blower tests might have some repeatability problems, too, but I suppose some preliminary tests with a single setup would help identify if there were problems in those areas.

We've got a dyno tuning session coming up at the end of April. The cars will have different ports, etc., so the tests aren't all that directly comparable, but it would be interesting to take some sound level measurements during the tests.

-Max

 

Maybe we could play some Dungeons and Dragons too. lol

Just kidding. Just sounds like a lot of work. Would people actually be up for that? Sounds like it would take all day and you'd have to line up all the exhausts and tools ahead of time. Sounds like A LOT of work and planning.


Cheers,
Joseph

 

Yeah, but how many times have you seen threads asking about flow and sound levels for the various exhaust options? There isn't a lot of data available.

-Max

 

Here's a link to the leaf-blower muffler test I was thinking of (it wasn't the turbo minivan guy, though):
http://home.earthlink.net/~tmahon281/image.html

More info on the leaf blower test rig (and lots of other stuff):
http://home.earthlink.net/~tmahon281/tech.html

-Max