I had built my own a long time again and just went for it, it had a pretty good rumble, I did not measure the lengths just followed what I thought was the best route. It was similar to the turbo car routing but on the opposite side. I also tacked all of it on vehicle to get everything lined up properly then removed it and finished the welds. There may be some magic length but over the equal length you may loose power it just won't be noticable on this engine. Have fun with it and go for it and keep the old ones incase something doesn't work out!