I'm looking for something with the sound of the Borla, not too loud but a nice sound when you punch it, good sound driving on the highway (not annoying or loud) but in a quad exaust setup?

I'm wondering if the quad setups have performance drawbacks or advantages though I assume that depends on the specific one, cat backs would be best.

Thanks

ZEES makes a quad for a GS4, not sure about a GS3. Checkout www.shinkairacing.com

spectraGS3 - TTE has a quad exhaust , but its only muffler. Only cat-back for the GS is the Greddy and Tanabe , but there not quad.

Go to www.cecwheels.com to check it out. I heard its not too loud. Not trying to scare you but be prepared to spend over 1k for them.

The stock lexus exhaust is so effecient it would be best IMHO to buy what you think makes your car look better. Performance gains will be minimal by installing an aftermarket exhaust. I brought the Greddy's first on looks second on hp.