exhaust leak?
 

I took my car to Mostly Mazda (they are related to M2) today to get some things checked out and to install a downpipe. During the downpipe install, one of the studs coming out of the turbo came out. Now they have provided me with 2 options - mount the dp with only 3 studs and hope there is no exhaust leak or they want to charge me nearly $500 to take out the turbo and remachine a new stud to replace the one they yanked out. I'm not in the mood to pay an additional $500 worth of labor but I do want my car running optimally. So can anyone detail for me the detriments of a minor exhaust leak between the turbo and the downpipe? Are these valid concerns:

1. an exhaust leak that high defeats half the purpose of having the downpipe (to get hot exhaust AWAY from the engine)

2. depending on O2 sensor positioning, if it is after the downpipe won't this affect the reading? An affected O2 reading may cause the car to run overly rich or lean?

3. does an exhaust leak count as additional back pressure on the exhaust system? it seems it would create quite a bit of turbulence in the exhaust flow.

What would you guys recommend that I do? I'm definitely not happy by the possibility of my car running crappier than when I brought it in for servicing.

nevermind
 

Nevermind. They got a new stud in there somehow so the downpipe is bolted on all 4 bolts now.

Why is my name underneath exhaust leak?
 

jjjuuuust curious

Re: Why is my name underneath exhaust leak?
 

Because were newbies, once you have enough posts it will change to something else:D Some forums you can change it yourself but I dont know if you can do that here.