Hello everyone. This is for those of you that have both NISMO exhaust and the RT cats. After installation of the cats, the exhaust is rattling with the cross bar underneath the car. I shimmed the bar as suggested, but it still rattles. I don't want to keep lowering that bar. Today, I scraped a little for the first time on a speed bump with this new combination. I still haven't installed the S Tune yet!!! Any suggestions? I know this is a sports car and it will be lower, but........

Oh yeah, I had to put two gaskets between the cats and NISMO exhaust because of the funny angle. Maybe if I reduce this to one gasket it will raise the exhaust just enough. I'll have to look at it this weekend.

 

i've scraped a little a few times with that setup, and i have s-tunes also.

about the rattle, i had the shims installed at Performance Nissan and no probs to date.

 

What size shims are you using?

 

Whatever Performance sent me. They were really helpful when I called. I think the problem might be resolved if I loosen all of the exhaust bolts and re-adjust everything. I don't know what else to do. I think the last thing I want to do is keep lowering that cross brace until the exhaust clears. Maybe when I put in my S-Tune, I will adjust everything. Right now, the exhaust sounds horrible......but with only ~150 miles on the new cats. I went to a local alignment shop and they gave me some 1/16th shims???Maybe I should bend some of the hangers to make the exhaust sit higher? Just don't know at this point.

 

Anyone els running this set up that is unhappy with the sound? Im getting ready to pull the trigger on this purchase. One of the reasons I was attracted to these were because people said they were not loud and did not change the tone that much. Now it looks like they make the exhaust alot louder. I also have the car lowered a bit more than S-tune. If these drop the exhaust lower I might have some issues

 

Lotus, don't base your decision just off of my issues. From what I hear, it is usually not this difficult. As for the sound, I will re-post after a few hundred miles to see if the sound had toned down a little. It is only bad in the low RPM's. I love the throaty sound when I accelerate. It is also still quiet at idle. The only bad sounding point is around 1,000 to 2,500 RPM. After that, it sounds great. So, please don't base your opinion on my post. I am crossing my fingers that the sound gets better and I am able to fix the brace issue.

 

i have the rt cats and nismo exhaust...what we did was loosen all the bolts then place 1 inch block in between the cross brace and the pipe and then tighten it all up ..remove the block and no more rattles.....pulleys go on next week

 

Great idea!!!!! Whose idea was that? That's why I like working with other people on projects. Not everyone thinks alike and grat ideas come out of this type of collaboration. Duflacci, how long have your cats on? Has the sound decreased? How has the sound changed? Hopefully for the better.

 

You should at a minimum be able to stick your index finger between the exhaust and the cross member.

 

I think I can slide a piece of paper between the two!!!! I am going to try the wood block method and see if that works. If so, I'll call it the Duflacci method!!!! I wonder if there are rubber hanger things that are a bit shorter if the Duflacci method doesn't work. I'll be sure to post what I come up with.

 

I stayed at a holiday inn express last night......

I just installed them friday with the nismo CAI so far I love the sound...keep ya posted

 

I have the same problem as mentiond above. I tried the shims Performance sent me but still had the rattle.

Let me know if this other idea works for you. I have been driving with the cross bar off for the last two months. The car does not feel as tight but it doesn't rattle.

As far as the sound, I think it has remained the same but I have become used to it

 

You are going to have to double shim it. I got a set of shims from performance and I still had a slight rattle. So I shimed again. And that did the trick for me. You can use some washers to do it.

 

I've heard all kinds of great things about the performance increase with RT cats especially when combined with an exhaust, but I'm a little concerned about the interference issue. Has anyone checked to see whether it's a problem with other exhaust systems? I know one guy who bought the RT cats and with stock exhaust, there were no interference problems. Has anyone had a problem with a Stillen or any other brand exhaust?

 

I had the problem with a Borla. Not so much with the center brace issue, but with the passenger side exhaust pipe hitting the rear sway bar. For some reason, the RT Cats are a little longer or are on a different angle than stock cats. This makes your exhaust system have a greater downward angle from back to front, which is why the shims are needed and why there is more of a chance of scraping on speed bumps. If the RT's could have been made to the exact dimensions as the stock cats, these problems would not exist. I know some people have had luck with using all four shims in the front. Two on each side of the front part of the plate and none in the back. Maybe that makes the plate follow the angle of the pipe(s) better.

 

Its very easy to do....just loosen the bolts at the y-pipe to cats and the bolts at the rear end of the y pipe put a 1 inch block between the pipe and the front end of the brace....{you can see the tick mark from where the pipe hits the brace}.....center the block under the tick mark on the pipe and tighten the bolts...then send the shims back for a refund take the refund and donate it to my350z.com..... LOL.... my advice may be taken with a grain of salt but its always free......

 

How are the dimensions of the crawford cats compared to stock. Will the crawford cats have the same problems? Anyone with crawford cats and stillen/nismo exhaust have any problems? Thanks

 

Just to let everyone know, I will be trying the Duflacci method tomorrow and will post the results. I know it's not as exciting as the new plenum dyno, but it will solve an issue that annoys the hell out of me. I also like the idea of shims on one part of the cross brace to match the angle of the exhaust. Maybe have to combine the two. Thanks for everyones input.

 

there is another way to fix this issue that we do at the shop but havent told people how to do this until now...

we tell people to do the shims because it is the easy solution...

if you look at your mid pipe it is being held up by a hanger with rubber insulator...

if you take the hanger that is attached to the under part of the car and bend it up it will lift up the mid pipe above the cross brace...

 

Jason, thanks for the advice. I tried a little tinkering today, but was unable to completely fix the problem. The good news is that I have heard the exhaust now when it does not rattle. I have to say that the sound itself, when not rattling, is great. It is like a more agressive factory exhaust note. The exhaust then opens up around 3k, but not as much as it did a few days ago. I think it is still breaking in a little, but it's amazing how much better it sounds now!!!! I actually really like the exhaust as compared to the fart can rattle it was making earlier. Since I tinkered with it earlier, the exhaust has some how settled again and makes the horrible sound again. I will try the bending, which sounds like a good fix to the issue. It is nice to hear the good sound coming from my car now. I was getting a bit worried for a while.