Autosol metal polish will clean it up really well
I've got a stainless steel catback on my VZ 1 Tonner and I noticed there was some surface rust on the rear muffler....Gave it a quick rub with some Autosol and when I wiped it off it was shining like it was brand new again
A little bit of surface rust internally isn't going to cause any issues
Yes have read that the hsv rear muffler doenst work with the ss bar and that the ss muffler sounds better anyway. Wonder if there is any internal difference as the hsv muffler is 2.25" on the intake. There fairly rattly anyway.
Rust is a little worse than I thought on the ends so will take to it with a wirebrush as well and hopefully reuse all the bolts and gaskets on the stock system. Inside looks fine though.
Maybe put some rust prime on joins as well to keep it at bay.
Update, so mild steel flanges were pretty average, so after 10 hours of flappydisk, wirebrush, hydrochloric acid and now phosphoric acid I am at this point.
Midpipes will be ready today and hopefully on, going to clean up Hsv mufflers for resell or to sit with stock exhaust.
Cats were the worst due to the rust getting in the mesh conatruction on the flanges, literally falling off after 10 hours of hcl acid bath.
Bought some metal polish and clear coat high heat spray to seal but can't decide which to use, probably the spray.
Anyone else wants to remove rust, hydro acid is cheap and works really well without much labour but metal will flash rust after drying. Phosphoric acid is apparently better but harder to fund especially concentrated. Grinding the flanges with a 60 grit flappy probably saved heaps of CID waiting time but is labour intensive as with the wire rushing which is pointless unless your at end polishing stage.
Why? The more I kept going the more I wanted to eliminate rust and see if polishing and sealing was possible. Wanted to acid wash concrete as well to paint so had a perfect spot to do it.
The Acid is hazardous so be careful and do at own risk.