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DIY Turbo Discussion greddy on a 1.8? homebrew kit?

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Old 01-20-2009, 09:56 PM   #21
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I completely dissagree with most of the people in this thread.

I have been looking at this exact same thing for myself.
A 3" exhaust can be made to be not too loud but be honest - it's not going to be quiet. Period. Plus, for maximum performance you need to toss the catalytic converter too which means testpipe and that adds to the noise level. AND, if you use a silencer to quiet the exhaust up, that is a restriction which hurts the performance of your exhaust that you just spent so much money on specifically for its performance. AND, you would have to pre-meditate any times you want to remove that restriction and remove it before you go out to drive. No thanks.

The cut-out could be done with flanges on both sides and put between the downpipe and cat (cut the last few inches off the downpipe so it fits). This way if you need to go to a ref or pass a visual for smog, you just need a short pipe the same length with flanges on both ends (think mini-testpipe) to bolt in instead of the cut out and you are good to go - no more work than swapping a testpipe for a cat.
The benefits of this are enormous - first, the cut out will give you better spool and performance than even the best full exhaust period. Plus, you keep the nice quiet exhaust for commuting and travels (I know I'd like it for those times) and you can drive around normally without attracting attention. PLUS, if you do get pulled over and an officer looks under the car to verify that there is a cat, you DO have the cat still - miatas are so low that on mine (lowered a lot) you can't even see the exhaust when you lay on the ground, just the bulge of the cat so the officer would not even be able to see the cut out but would see the cat there and you would be OK.
AND it costs less.

Cut-out FTW.
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