has anybody just put a high flow cat and good muffler on their stock exhuast? I dont really have the money for a full exhaust system rite now, so i was wondering if i could just buy half now and half later. Would it sound good if i did that?

why not just gut your cat and take the money from a hi-flo cat and use that to get the piping thats what i did

-nowitzon+May 3, 2005 - 8:35 PM

Modern three-way honeycomb cats are not a significant airflow obstruction. A gutted cat, however, is, since the enlargement in the pipe allows the gas to expand, cool and slow, forming a barrier for incoming exhaust gases as you try to force the expanded gas back into the narrow post-cat exhaust piping. Better to leave the cat intact (and hey, we're going to be breathing this air for a while, so why not keep it clean) or replace it with correct size piping.

A good high-flow cat (which pretty much describes every modern cat) with universal fittings will only run you $50-$75 dollars.

Not terribly familiar with sixth-gen emissions, but it the cat you want to replace is the one right up under the exhaust manifold, don't bother. Too bloody expensive because it's a specific fitting. If it's an underbody cat, you can certainly replace it. One idea I've come across is Car Sound's (MagnaFlow's parent company) combined resonator and catalytic converter. It eliminates the resonator that comes after the stock underbody cat, which removes one, albeit minor, flow disruption in the piping.

Good muffler for flow invariably means bad muffler for noise suppression. A straight-through muffler, which basically invovles insulation wrapped around a perforated pipe, isn't all that good at suppression. Flows great, however. The more offset between the inlet and the outlet, the more suppression, though you lose about 10 cubic feet per minute in exhaust flow -- not really an issue with our engines.