SCCA exhaust question
 

I understand that the exhaust has to end behind the driver but does it have to exit out the side or the rear? also is a mufflef required. kind of falls into line with my first question. I may do a muffler delete on the rear but can i just end it under the car and not have to worry about tips. If not, im going to have a set of pipes made to exit the rear of the car. I will have it bolt up so i can change the straight pipes and the mufflers just for autox. basically, do i need axle backs or not?

Looks you are in ASP per your mods. You don't need any mufflers, etc but the exhaust must exit behind the driver. Does your region have a sound restrictions? Since you are out in HI, you don't have to worry about the 99db national sound limit (was 100db last year).

thanks for the quick response. the exhaust ends right after my rear diff so im fine there. glad i dont have to meet the 99db rating cause i dont think i would make it without a muffler lol

In theory all SCCA sanctioned events are supposed to abide by the 99db maximum. You may very well be asked to leave or fix it if you show and start blowing 110db. Almost all regions (except those like San Diego, New England, etc) don't measure sound at their local events. That said, as Shamu stated, you should do your best to abide by a reasonable sound level. In DC, we are located right under the Andrews AFB flight path for C130's, etc...so sound isn't really concern for locals. They have to deal with Jets at less than 1000' all day every day.

Better be fast if you have an open exhaust, else you look like an a$$hole

Check with your track, and organization that your going to be racing at and with. Some have noise decibel restrictions, or time they are restricted.
My local track Portland International Raceway has a decibel limit of 105 dBA limit measured trackside. Though depending on race or time they allow varianced events include one event at 110 dB, two at 112 dB and one at 115 dB at trackside, and I believe during dragracing after 9pm 98 dB is the max.

thanks guys. i honestly couldnt tell you if my car really breaks that 100db point. a lot of people(friends and other car enthusiasts) are telling me that my car isn't actually that loud. a lot of people are still very surprised that I have headers and test pipes with no muffler and straight pipe. Theres a guy with a G35 here who everyone says hes still louder. it may just be loud to me as Im not use to it? ill search to see if there somewhere i can do a DB test as i don't want to get axlebacks made and not be able to use em. As i said, this is purely for autox and my mufflers will still bolt back on after event. not sure if noise is an issue since the course is run in the parking lot of Aloha Stadium surrounded by 2 major highways. Thanks fir everyones input and feedback!

I run long tube headers that come together at a 3" collector. That goes through a 3" ID x 6" OD x 18" long resonator and dumps straight down behind the Cabin and I was on the SCCA limit at Nat'ls. The car is PLENTY loud made tolerable by the purr that Nissan's are known for. When I'm on the pipe, it's music.

Please run through at least one big straight-through resonator or two small ones and point all that to earth!!!! Besides you don't want to give up too much low-end torque with an open system.

Guys like me (and plenty of others here), who play by the rules, don't want the limits dropped because of those who make too much racket...:driving:

my test pipes i have are resonated. also where my exhaust ends right after the differential, its a true dual exhaust and each side ends at an 18" resonator. thats probably what keeps the noise down. so it goes through 24" worth of resonators before it exits. my exhaust is also only 60mm piping. (2.36")

Ah man...your good. Happy racing!

Yeah, we're stuck with a 93dB limit out here in San Diego. I couldn't imagine how loud 110dB would be.

Just wanna say thanks for everyone's input! I actually ended up bolting the mufflers back on cause the bottom end loss was VERY noticeable and I love my torque. Had my first event a Sunday and went very well! I posted a vid under a different thread. Just wanted to reply to everyone back in here that helped me out.