First of all, I wouldn't recommend doing this to your only set because you will likely run into problems at inspection/emissions or when you sell the car. I now have a 350Z and I still had the stock cats from my G35 that was totaled. After trying to sell them (cheap, $75 shipped BTW) for the last couple weeks I decided to just keep them and gut them out. After having the Borla exhaust + Kinetix resonated test pipes on my G35, the stock exhaust just wasn't very satisfying.

I am very pleased with the way things turned out. No SES light (early 04 model) and the rasp is almost non-existant. It sounds very similar to stock but is noticably louder at all RPM's. I still get a faint gas smell with the windows down at idle, but it doesn't seem to be as bad as my G35 with the Kinetix pipes. I might pick up a Borla exhaust if I can find a cheap used one because I do like the deeper tone, but right now this will keep me happy and best of all it was free.

 

yes. this is exactly what i did, i bought a set off some guy on this forum for $100..and it works great! no rasp at all and there some gains. i too have the faint carbon monoxide smell w/ the windows down.

 

If you want a good used Borla TD exhaust I have a friend that is willing to sell his for $400.

 

I have also thought about doing this. The only thing stopping me is the thought that even gutted cat pipes are far more restrictive than any brand of straight test pipes. Then again, I hate that rasp and have thought many times about just putting my cats back on, gutted or not.

 

CO is odorless.

 

If anyone is interested. i have a set of gutted cats for sale
pm me for the details

 

yes but uncombusted gasoline is not

anyway back on topic... for those with gutted cats, have you dyno'd? Just curious. I'm wondering if gutted cats performs as well as test pipes (and leans out the mid-range just like TPs)

 

It can't be good for your brain... especially come winter time I think I lost a few cells in my old 86zx, it had a manifold leak somewhere... I hope my HELIX HF's don't emit anything!!!!!!!!!! Another reason I stayed away from the TP.

 

Damn i need to find me some stock cats and gut them, should be much better than my test pipes. BTW how much of a gain did you feel in HP compared to non-gutted cats

 

Let us know how you like them. I'm looking into these but haven't seen anyone's impression on them. They look like higher quality than the Crawford or Kinetix high flows.

 

u think the res test pipes might be a little better as in performance wise? cuz in the gutted cats, the air tumbles around unlike test pipes where they flow straight out.

 

So you're using these with the stock exhaust? How much louder are we talking, exactly? I had high flow cats on my Nismo exhaust for a while, but the loud droning on the freeway drove me nuts. I ended up putting the stock cats back on with my Nismo exhaust, and that quieted things down significantly. I recently bought a set of used stock cats from a guy here with the intention of gutting maybe 1 or both of the cats in each side. I figured gutted stock cats were not going to be much louder than stock, but it sounds like you're saying that are.

 

I have my Stock cats in storage, if anyone wants them I'd be more than happy to sell them.