collector extention length
 

Made some extentions extra long and want suggestions on optimal length.have seen guys put paint and grease on them.they would do a run and cut where the paint or grease quit burning off.also saw some one wait for a blue ring to develop and cut on the back side of it for best results.

If you are not seeking every last spec of HP from your motor than the burn the cheap paint off deal will work fine!
Since you did not state what CID motor you are talking about, nor its max rpm then in general 14 to 18 inches will do it and if the motor never really see's over for 6k RPM for more than 3 seconds on a run then a 18 inch lenght will sever you the best!

Anything between 12 to 18 inches will get you in the ballpark, the merge style and flowmaster collectors are a bit better tho! :cool:

I put 3 1/2" dia. 24" long extensions on my 3 1/2" collectors. Never cut them down to the length where the paint quits burning (looks to be 16"-18"). Am I giving up a little HP there? I like the way it quiets down the exhaust inside the car. Sounds better outside too!