More Exhaust Stuff

[TWFAUST at aol.com]

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       This is not scientific, but is real world. I number of years ago I
passed some time stuffing a Chevy 350 in to a 1978 Z. Exhaust room was tight.
After a lot of consulting with other people doing the same, it turned out
that the Dyno's had shown that single 2.5" pipe was optimal. No significant
gain was shown with a 3 inch pipe. Dual 2" pipes, showed a small gain. That
may have been attributable to manifold design.
       Granted, these were NA motors, but a 6 liter motor has to pass a lot
of gas. It has long been understood that some degree of back pressure was
advantageous. This may not be the case with turbos.
       I suspect that so long as the turbo outlet port and the cat remain the
same, "cat-back" systems can only show a slight gain at best. I suspect that
removing the cat and installing one of the "test" pipes that J.C. Whitney
sells would probably show the most bang for the buck at about $14.00.
       Since I long ago gave up the assumption that there are any secrets
hidden in the Sharvtzenwald (SP) I would suggest contacting Hedman Headers or
one of the other hot rod exhaust people. Those boys know from flow.
Tom Faust