Hello:
I have a 91 cierra and have had to replace the muffler myself, I thought it would be easy but ended up taking me a couple of days, I had a liminted amount of tools, and had to go out and buy some torches to get all the parts off.I would suggest getting it fixed by a pro, it will be more money but less aggrivasion, you could try patching it but it will most like not last a long time.
As for driving it without the muffler attached, . Go for it, but make sure there are no noise laws on vehicles, . When I had my muffler off I drove to work one day and was pulled over by the police for a loud vehicle, . He let me off with a warning. But it will not hurt your engine.
Hope this helps
Paul
Wednesday, September 27th, 2006 AT 2:57 PM