Actually after racing for many years making various length headers and collectors we have found that 18" of 3" pipe works best for engines from 300 cu in to 350 cu in. Most tracks are requiring a short muffler to meet decibel limits. On a SL6 I would think 18" of 2.5" pipe would create max torque.

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

cool, ya i had these kicking around and mentioned them on here......its neat to see how designs have changed over the years due to extensive racing an testing