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[6G96GT]

Curious...the 2nd cat that connects to the muffler...couldn't I remove it and then cut it open, gut it, and then weld it back together again and now I have a straight pipe basically into the muffler instead of purchasing a resonator??

what's the actual difference between that and a performance resonator?

[Galcobar]

Gutted cats create turbulence in the exhaust stream and therefore diminish exhaust flow -- making your exhaust system and therefore your engine less efficient. Unless your cat is clogged by years of poor running conditions, it won't improve exhaust efficiency over leaving the cat in place.

Secondly, make sure you understand what a resonator actually does. It is NOT a round-body mid-muffler. It is in fact a carefully designed echo chamber whereby sound waves are bounced into each other in order to cancel them out without slowing exhaust flow. Missing the resonator is typically the reason for the nasty buzz on aftermarket or custom exhausts. A resonator is primarily meant to smooth the tone of your exhaust, while a muffler's main job is to reduce the volume. The round, straight-through mufflers so often advertised as resonators may resemble a real resonator from the outside, they are unalike in construction. Easy test: a resonator will ping like a bell when rapped, while a straight-through muffler will absorb the sound via the insulation with which it is packed.

Stock Celica exhausts have resonators under the body, not mufflers.

A good-quality straight-through muffler will reduce your volume, and the upside is that a longer or larger model will reduce volume with negligible exhaust flow impairment compared to a smaller version (with baffled mufflers, bigger meant quieter but much more impairment). MagnaFlow makes a good straight-through muffler with a smooth inner pipe and insulation composed of stainless steel wool and ceramic fibre; Cherry Bomb is 1950s technology with a louvered inner pipe (think of the effect of a hundred little scoops cutting into the exhaust flow) and fibreglass insulation.