BrianLG35C

iTrader: (2)

I got rid of the rasp sound for good! Much better sounding all the way through the rpm range. A little more restrictive so I may of lost high rpm hp but I can still chirp in 3rd gear. It's worth the very slight hp loss (if any) for the much improved sound. If you're sick of the crappy sound you're getting from the RTs then consider switching. Thanks Adam at Z1 Perfomance!

Now the problem!! I picked up my car from my dealer on Friday night and drove it home on the highway for an hour or so, enjoying my new, more mature sounding exhaust. When I came into town and noticed a strange new vibration coming from somewhere underneath the engine compartment. I could feel the vibration when especially accellerating in first and second gear but once I got going it stopped. The strong vibration even comes through the gas pedal and interior. The engine also stumbles and hesitates when out of gear. I never had these symptoms before the switch. Could my Infiniti dealer not installed them properly? Is that possible? I'll call them early in the morning but I was wondering if anyone would have any ideas what it could be. I'm freaking out a little and don't want to do serious damage just driving it an hour to the dealer.

Thanks for any response.

BrianLG35C

iTrader: (2)

Anyone have any ideas. If it's the Cats causing the vibration, why do I have the engine symptoms? Could it be the ECU resetting?

LowUFO

It sounds like it might be an exhaust leak. Try looking under the car to see if you have any carbon coming from any of the gaskets. Try tightening the bolts, etc. Did you use new gaskets? They may need to be replaced. I'd start there. I had a similar problem with my Integra Type R, and it was a crack in the flange, and it was leaking. I had to have a replacement CAT sent.

Ian

BrianLG35C

iTrader: (2)

They were supposed to use new gaskets per my request. Thanks for the input.

apex locator

iTrader: (5)

yup, nismo + RT cats = raspy sound at higher rpms. i had that combo for ~1 year and recently switched out my complete IHE setup. went with ultimate cats also and like the sound w/ the borla td (quiet). ultimate cats are indeed a tad more restrictive.

shortcut3d

Ultimate cats are great. They are not loud and this is the only mod I notice a perceiveable difference. 3K and up is insane with the Ultimate cats. The build quality and fit is also excellent. I swear by them now.

EL Diablo

I have the RT cats and NISMO exhaust and like them

Yes they can be a little raspy in the higher RPM's but its never bothered me.
I wouldnt say it's a crappy sound at all.

I'd love to hear a sound clip of the Ultimate Cats and the NISMO exhaust

are they as loud as the RT's ?

owali1

Where did you all buy the Ultimate cats? I was thinking about getting some as well.

Glasgow Smile

iTrader: (1)

Z1 Performance a Vendor on this board.

http://www.z1auto.com/

GurgenPB

iTrader: (2)

If there is vibration, i can ALMOST GUARANTEE you that the cats are hitting the body wall of the car. My G had the same problem as I was trying to put on/fit the Crawford (and later RT) cats designed for the Z. It's a relatively easy fix: you have to hammer in or somehow modify the body wall to make room. In my case, we made an "X" incision in the wall (actually a double wall on that part of the chassis - so definitely no big deal) and hammer in the triangular "flaps" create by the incision. This gave us the necessary room. Problem solved.

You can of course check whether this is in fact the problem by taking off the cats and looking to see if there were any marks/scratches (from rubbing, hitting) made on either/both the cats or the chassis wall itself.

Gurgen

BrianLG35C

iTrader: (2)

Thanks gurgen. I'll take a look at the body wall asap, but I didn't have this problem with the RTs so why now?

GurgenPB

iTrader: (2)

they could be of slightly different shapes. My RTs ALMOST fit, while my crawfords (slightly larger size) are the ones that really required a modification.

BrianLG35C

iTrader: (2)

Ok. But the thing is, the vibration doesn't happen all the time. Only after I've been driving for a while. Do they expand slightly or could it be something totally different?

Z1 Performance

iTrader: (564)

Brian - check that you don't have a loose heatshield, or an exhaust leak

GurgenPB

iTrader: (2)

i think that vibration is due to rubbing/touching ... who knows how that happens... you gotta get down there and check

Gurgen

chops

I ditched the R/T's for the Crawfords. The Rasp is now gone!

btw, running Stillen Exhaust on a G35 Coupe.