750 sx sxi factory pipe help

Bought a kawasaki 750sxi. This is my first project ive done. And i was in for a big task, because there was hull hair line fractures, and lots of cosmetic restorations I had to tackle. You'll notice i redesigned the back tray area. I gave it a different shape that would go better with the Toms...

I have a 750 sx and my factory pipe bolts keep backing out of the factory pipe mani.... Have re-tapped the holes and tried red lock tight but still no luck... Any ideas??? Upgrade are in pictures.