I just installed the nismo exhaust & crawford cats this past weekend. The install was a piece of cake. I have been experiencing a pretty loud drone between 2500-3200 RPM's. I get this in whatever gear I am in when I just barely touch the gas or lay off the gas & let the car slow down. I was just wondering if this is normal, or if I have a leak somewhere? I read previous threads about the drone on the highway, but are you guys also getting it in lower gears? I know the sound should mellow out with some miles on it, just wanted to get some input from people with this set up.

 

I got the DC headers with the nismo, and YES I get the EXACT same thing. If you pay close attention, I think the drone has something to do with the backpressure, ironically, this is an RPM range that I can feel a significant increase

 

Thanks for the reply. The drone is a little annoying, but I'm sure I will use to it. I hope it will mellow with a few more miles on the exhaust. Anyone else experience this?

 

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Yeah, that's definitely normal. I had the same problem. I guess I'm overly sensitive to freeway drone, though, so I actually had to put my stock cats back on to quiet the Nismo down. Just couldn't handle it on long road trips. Fun around town, but a real pain in the rear if you have to drive on the freeway for hours at a time. To be honest, I might be going back to the stock exhaust because even the Nismo with stock cats gets on my nerves a little on long road trips. I guess I'm an exhaust weenie. The stock exhaust with HF cats wasn't a problem, though, so that's probably the config I'll end up with in the long run.

 

So how much of a difference in sound is the nismo exhaust with the stock cats compared to the crawfords? I'm already starting to get used to it, but would like to know for future reference.

 

With any HF cats the sound will be quite a bit louder. I took measurements with an SPL meter during freeway cruising and posted them in a past thread. (I don't recall them off hand.) Basically, the droning in the cabin becomes quite a bit louder with HF cats, and it's even worse if you get (unresonated) test pipes. With stock cats, the Nismo exhaust is actually not much louder than stock when cruising on the freeway. It does have a little more drone on the freeway, especially if you're going very fast or up hills, but it's not anywhere near as loud as with HF cats.