Everyone says to put the cutout at the axle but then my airflow would go through my cat. The only difference would be no muffler. I was hoping to skip my cat as well as my muffler

 

It will sound incredibly loud and really resonate the floor pan. I used to run them on my GM cars and always run them at the back axle. It can be done before the cat, but will probably sound like open headers.
jmho

 

If it feels anything like open headers, you'll wish you had never done it after a day or two. When I had open headers on my Z for a couple days, it was incredibly loud and felt like it was going to shake the entire car apart. I'm not exaggerating one bit...it really isn't something I would have wanted to deal with for any longer than I did. Put the cutout behind the axle so you'll at least enjoy using it. If you put it before the cats, it'll be so loud that you won't want to open it up.

 

The cat is robbing you of very little power if any, if that is what you are concerned about.

 

I love my headers that go to my y that goes to my electric cutout. I have the stock exhaust after that, so it can be quiet for highway and puttering around town (yea right) use. But even through the stock muffler it gets much louder after 3k =) What can I say I like to scare the ricers sometimes. Or just **** off drivers with rolled down windows that pissed me off first by driving like idiots.