[Jake]

I have an 89 mx6 gt turbo 4ws, and recently I started getting a low virbation at around 2900 rpm in any gear. It sounds almost like a hole in the exhaust... But it goes away higher than 2900 and not there below it. THe car has 112k miles.

 

[kennymx6]

Funny, mine does the same thing. I have an LX with the automatic. Whenever the car goes into 4th gear it will make the noise for a second or two, depending on how much the engine is being lugged. I believe mine makes the noise form the manifold, either were it meets the downpipe or the engine. Yours is most likely making the noise where the downpipe meats the cat. In that location there is a spring loaded flexible joint.

 

[Jake]

Vibration

Im gonna get a custom exhaust this weekend at my cousin's Midas shop with a hi flow cat and 3 inch pipe to a big pretty muffler...

They can find the vibration...

I wonder, should I change the downtube?

 

[anarchyx34]

yeah change the downpipe too, if you can afford it. The downpipe needs to be mandrel bent even if the rest of the exhaust isnt. YOu wont be able to use 3" pipe there (well, not easily). But 3" for the whole exhaust is kinda overkill IMO, unless you're using crimp-bent pipes.

 

[Guest]

Re: Vibration

Im gonna get a custom exhaust this weekend at my cousin's Midas shop with a hi flow cat and 3 inch pipe to a big pretty muffler...

They can find the vibration...

I wonder, should I change the downtube?

Just as a warning, you are going to loose all low rpm torque and drivability. If you plan on doing a lot of racing and need hi rpm horsepower then change the downpipe to header, cause that is where the most restriction is and use 2 1/2" pipe. Otherwise keep some backpressure and keep the downpipe and use 2" or at most 2 1/4" catback with free flow converter and muffler. Just a suggestion.

 

[Jake]

Canfind a header

A header? On a turbo car? How does that work? The exhaust manifold comes right out into the turbo, then there is a downpipe.

So I should get a bigger, free-er flowing downpipe then?