[damage]

Easy, straight side pipes no stuffing or anything was 109db at 3600. Inserted cats and this dropped to 99db. Inserted louvred plates borrowed from renovation which basically shut the exhaust opening down about a 2 1/2 inch opening and I achieved spot on 89db.

Engineer said he was happy.

Car with the same configuration after driving around and carboning up the exhaust is 2 db quiter.

If I wanted it to be permanent I would fit an exhaust auger.