High Flow Cat vs Aftermarket Exhaust

[Sky Hi]

Has anyone compared performance gains of the aftermarket High Flow catalytic converters vs aftermarket exhaust? Some stock cats look like they may be more restrictive than standard mufflers. Which gives the biggest improvement? Would a high flow cat change the exhaust sound level much? Is a high flow cat likely to wear out sooner and cause an emissions idiot light to come on?
Thanks

[RPIpower]

The cats wouldnt change the sound because none of the material inside the cat was meant to muffle sound. Some people have tried to "punch out" their cats but there was no sound difference. Now, as far as flow and performance, both can play a significant part. Changing the exhaust could improve on hp based on how restrictive the stock system was. The stock muffler is very similar to the 3" magnflow system's muffler. If your car is NA, I wouldn't worry about changing to a highflow cat. For turbocharged cars, the cat being so close to the turbo exhaust housing, it could hurt performance. Like anything else, there are acceptions. Different cars, different characteristics, etc. This is something that would be fun to test. Too bad you are so far away, we could do some dyno tests.

[Devil Dog]

Swapping to a hi-flow converter, weather it be ours or another brand, absolutely makes the exhaust louder. The stock converter, though huge, is much more restrictive than the hi-flow. In normally aspirated form, the more power an engine makes the louder the exhaust tends to be. For instance, when i swapped my stock engine with a 383 in my 95 Impala SS, and made no other changes to the exhaust, the volume increased dramatically. The engine was also dramatically making more power.

In a nutshell the hi-flow converter does increase the volume of the exhaust on the Solstice and Sky. Not to an extreme but definitely noticable.

[RPIpower]

Intake and exhausts make the bulk of the noise so moderate change in horsepower is not going to make your car any louder. Changing the compression etc. and other internal engine work might cause engine noise characteristics to change. On the 1nzfe, we increase power and torque to the wheels by over 40% and the car made no extra noise between a test pipe and a cat. Your muffler and exhaust piping system will make the bulk of the noise.

[Sky Hi]

Guys,
Thanks for the responses. I am putting the factory dual exhaust on my 2.4 NA, because I didn't want a louder exhaust while cruising at low RPM. While I know it won't add the power of some aftermarket exhausts, I was wondering if a hi flow cat would be worth adding, and keep the noise level close to stock(or a little louder).
Regards,

[RPIpower]

Originally Posted by Sky Hi

Guys,
Thanks for the responses. I am putting the factory dual exhaust on my 2.4 NA, because I didn't want a louder exhaust while cruising at low RPM. While I know it won't add the power of some aftermarket exhausts, I was wondering if a hi flow cat would be worth adding, and keep the noise level close to stock(or a little louder).
Regards,

Depending on how efficient the stock cat is you may get a performance advantage going with the high flow cat. If you are using the stock RL exhaust, you shouldnt have any problems especially since there is a secondary resinator.

[SKY Spy]

BA...