maybe the newer ones flow more? just a thought, my friend and i went to get tuned and we had everything the same except the i/c he had a stock mount greddy and i had stock, and the catback were different, he had the old rb duel and i had some crappy universal silencer (came with the car). we got tuned a day apart, i asked him how he was doing with the creep and he said he didn't have any. i asked steve and he said the rb duel do restrict a little so that's why he wasn't creeping. i now got my new rb a couple months back and i still creep like i did when i had the other exhaust... but i don't doubt it restricts some air flow

 

Have a look at this thread...

https://www.rx7club.com/canadian-forum-42/new-exhaust-less-backpressure-more-fuel-853587/

I made 415 rwhp @ 18 PSi with a 500R-SP on a Mustang dyno with my old intercooler setup (which was slower) and the Racing Beat dual-tip.

After installing the new titanium fart can exhaust, I had to add 6% of fuel at 7200 RPM. My backpressure dropped from 10-11 PSi to 3-4 PSi with the new exhaust. This was at 17 PSi dropping down to 16 PSi at high RPM.

The Racing Beat is definitely an awesome exhaust for the street. It allows 400+ rwhp with the proper setup. However, if your looking to extract power, it will be a restriction. I'd say its probably the ideal exhaust for most people as its nice and quite.

Even though my Amuse is louder, it doesn't seem to bad. I like the deeper tone better. However, at times I wish I didn't have it, especially late at night.

thewird

 

...............
Another exhaust to consider, thats looks a bit better then the dual tip is the new Tanabe Medallion Concept G .. Its cheaper then the RB as well ..
I just installed one on my car & love it ..
Its very mellow, but comes on nice under power ..
Im in the same boat dont want to draw unwanted attention ..

 

I recently replaced my RB single tip exhaust with a N1 style Jasma approved catback, i did notice the difference with both power and noise. i would rather add a resonator before i go back to the RB catback.

i have 3" midpipe with highflow cat.