High Flow CATs
Thread Starter
Burning Brakes
Joined: Nov 2011
Posts: 1,030
Likes: 54
From: Chandler, AZ
St. Jude Donor '12
High Flow CATs
Has anyone ever really checked to see what is the gain by just changing out the CATs for high flow vs. stock? Would you notice anything? Maybe better mileage? Response? Please chime in if you have knowledge in this area. Thanks.
Melting Slicks
Joined: Feb 2009
Posts: 2,857
Likes: 234
From: SW Nuh Hampsha
2018 C5 of Year Finalist
I installed free flow cats, along with an x-pipe and Z06 ti exhaust, all at the same time. The car was considerably more responsive. I remember thinking "wow" the first time driving it. It felt as though I had removed a cork from the exhaust system as I could actually "feel" the exhaust flowing "faster and smoother". Not something you'd realize until you do it.
I attribute the improved flow to the cats (85%), the x-pipe (5%) and the ti (10%). Just a guess on these numbers. My car had 65,000 miles at the time, so I'd imagine the original cats were getting close to their expiration and were fairly clogged. A car with considerably fewer miles on it probably wouldn't yield quite the difference that mine did. Still, if smog regs aren't a concern, I'd do it along with at least an x-pipe. And while you've got the exhaust out, throw in an insulated tunnel plate.
I attribute the improved flow to the cats (85%), the x-pipe (5%) and the ti (10%). Just a guess on these numbers. My car had 65,000 miles at the time, so I'd imagine the original cats were getting close to their expiration and were fairly clogged. A car with considerably fewer miles on it probably wouldn't yield quite the difference that mine did. Still, if smog regs aren't a concern, I'd do it along with at least an x-pipe. And while you've got the exhaust out, throw in an insulated tunnel plate.
