D Max has informed me that my stock exhaust on my 65 M20E has passed away.  In considering a replacement or repair, I've looked into a complete rebuild ($1800.00) or a Powerflow system ($4,000.00).  I've been told by my shop that he has have removed as many of the Powerflow systems as he has installed (excessive noise seems to be a major complaint)  I've read about the advantages of the Powerflow but I'd also like to hear from anyone who has had theirs removed and gone back to stock and why.  I