<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by 99 Sidewinder:
Does free flowing cats change the exhaust tone?
Are they louder that the stock cats?How much performace gain are they worth over the stock cats?Thanks for any info...
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Hi flow cats work as an integral part of a complete SYSTEM.
Generally, the higher-flowing cats deepen the sound, and MAY increase the volume, but only IF the rearward restrictions are minimized. Deepens and gets even louder with free-flowing performance headers.
As far as HP gains, AGAIN, the answer is based on all the other components of the SYTEM...and THE YEAR MATTERS!
If you simply add hi-flow cats to a stock Gen 1 car, and do NOTHING ELSE, you'll gain ~~10HP and waste $$. However, as an integral component of a performance exhaust SYSTEM, those same cats might free up 15-25HP for a header/cat-back system vs. STOCK cats. Gen 2 a bit less. 2000-2001 a bit less again.
A bonus: less sidesill heat. OE cat heat often discolors paint.
And NOT ALL CATS are created equal! The $1500 honeycomb metal substrate cats of the 'V-12 BMW Tuner Set' are now available for Vipers, still at a hefty $649/pair, DOUBLE the price of other hi-flows, but give +5~10HP over ceramic.