Alright here is the setup I am getting ready to put on:
3" evo2 catback
3" downpipe for a star turbo kit
3" test pipe (flex pipe?)

My question is, since there is no flex pipe installed to the downpipe would I be able to just install the flex pipe behind the downpipe where the cat would be (kinda like a test pipe)? Would it have enough flex if I put it in that spot? I know this is a dumb question but I have broken my fair share of manifold bolts because of no flex pipe, so I just want to make sure it will work.
-Todd

Sure...why not? Just buy one, cut out the same length section in your DP, and weld the flex section in....or have a shop do it for you.

*edit*

Sorry I missed your point. To answer your question the the flex section would have to be as long as the CAT (hard to find and super expensive) or weld extensions on the flex section. Then you would have to have the correct flanges welded on. IMO what I said before would be easier and more cost effective. Unless there is a product for us that I'm not aware of especially designed for this. :shrug

I want it to look like this:


It comes out cheaper to do it this way then to have to buy a high flow cat or have an exhaust shop cut my dp to weld the flex pipe in and make a test pipe.
-Todd

The reason the flex section is usually where the word "downpipe" is in that diagram, is because the engine rolls forward and backwards on its mount. If you move it back, it'll have to flex even more, so you might want a 2x longer flex section.

One other question, if I dont install a high flow cat and just put in straight piping will the car sound raspy in higher the rpms? I read somewhere that it would.
-Todd

I think your idea would work, but I would push the flex pipe all the way forward, ie, bolt it directly to the DP and then use your "extensions" on the exhuast side. That way the flex pipe is closer to where the motor movement actually occurs.