Hey Bill. I am not running any heat shields on my delsol. I have not since last year and there are no adverse affects besides the temperature inside the car is a little warm after hard driving. The heat shield around the cat really only serves the purpose of helping the cat atain operating temperature faster. I had to remove my rear heat shield above my exhaust piping because my new header pushed the whole system back about a half inch causing the pipe to vibrate against the shield making the same really annoying vibrating sound that you seem to be experiencing. After removing the sheild everything was great.

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TampaSol
94 delSol VTEC
00 Civic Si
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