Pardon my haste in the original reply. The butterflies are very similar to the original, with the exception that we have devised a new way to make them that doesn't require drilling through the housings. Can't say more right now other than we do NOT use epoxy in the housings and NO sealing problems. Don't expect any. Also we DO NOT weld to the liner as sometimes pushed by others. I do not believe you can weld to the liner without catastrophic failure later. I believe you will either fail your apex seals or crack the weld due to crystallization of the steel. The muffler is a MAJOR win. It is quieter than a unmuffled Lyc, and successfully kills the annoying hi frequencies. It is more restrictive than some but only costs us a few HP. It also fits in an RV-3! I am experimenting with a larger version in hopes of repeating the success with a bit less restriction on cowls that aren't as tight as the RV-3

Bill