Previous the car had a 3" H pipe into 3" Flowmaster 2 chanbers and 2 1/2" mandrel tailpipes(NMCA rule). Open headers the car generally ran anywhere from 0.1-0.3 seconds faster depending on the cam/headers. Making the tranny convertor swap we noticed that the old system has some rust so we removed it compeletely, not even pipes on the car. Did some track tuning. Then added the 3" Dr. gas X, 3" welded ultraflows, 3" mandrel tailpipes and the car ran the same even with the extra weight, and is so much quieter.Mike Cooke on his old red TA also felt going to a 3" system helped get his car in the 10s.
The 400 also picked up with 1 3/4 over 2" headers into that first system. The RAIV heads had a reversion issue with the slow velocity of the larger 2" headers. So velocity can be an issue on the back end even with a low restriction muffler.
Swapping front "skinnies" picked my car up 0.1 over 15x8 snowflakes also.
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