Is it worth it? I am going back to BSP next season and want a competitive setup. The suspension/wheel/tire equation is set, and I'm looking for a little power. I have some HFC's and aftermarket intake and plenum. I'm sold on getting a Technosquare computer tune to get the most out of the motor. Would it be worthwhile to get a cat-back exhaust? The OEM one flows pretty good and is quiet. Any recommendations? I like to hear my stereo on long drives, and would be willing to spend up to $800 for something used that makes more power than noise.

 

Putting an aftermarket exhaust on a 350z from a competition perspective is more about weight savings than horsepower. You may gain a pony or two but the stock exhaust supposedly weighs somewhere between 50 and 67 pounds. JIC titanium single weighs 13lbs and sounds like pure sex.

 

Sorry, I'm probably not going to help much here. I've only autoXed a few times years ago so I might not be the best to offer sound advice. Take what I say with a grain of salt.

Anyway, any advice given will depend on a few things: How competitive are you right now? How are you placing in your regional events? Consistently top 3? Are you looking to do the Nationals anytime soon? How long have you been autoXing? I think the tendency is to mod the car too soon, and not truely confirm that gains are true. Personally, I think seat-time and instruction from the top drivers is the most over-looked aspect of autoXing, not saying this applies to you. Just need to make sure.

During my time autoXing, I never saw the point of modding the intake, header, and exhaust. That money could be used for tires and seat-time. Driving around mainly in 2nd gear is hard to see worthwhile gains from those expensive parts. Upgrading the suspension (assuming it is dialed in correctly), tires, wheels, and brake pads, sure! Intake, header, exhaust? I don't see the point. If you are running in the top of your class consistently and might be held back from placing First because of lack of gainful mods, then sure, mod them if they REALLY help. I think that's a VERY tough question to find an answer to though. I questioned whether these "mods" actually decreased torque throughout the RPM band while driving around in 2nd gear, something very important in autoX. You will need to see some back-to-back dynos of cars with different exhausts to truely know.

I've seen some impressive driving from people at autoXs in stock cars, sans tires and brake pads. They made me a believer when it came to mods, in that they really aren't necessary if you are really there to improve your driving, and that mods could actually hurt your car's performance.

Hope that was helpful. If not, please ignore.

 

Then I'll elaborate a bit. I have been autocrossing monthly for 5 years. I have taken the Evolution course and participate in drifting and HPDE's. I frequently drive other people's cars for the first time and get better lap times than them- all in the name of showing them what their car can do. I hold office and maintain the website of our local SCCA club, so I'm involved. Sure, I have a lot to learn, and this is not meant to show arrogance- merely perspective. There are a lot of guys who could get into my car and drive it faster than me, too.
That being said, I spent a couple years campaigning a Dodge Neon in DSP with non-R-Comp tires. I had non-removable mods done preventing me from running in STS, but I wanted to learn to drive on street tires first. By the time I got the car and my skills good enough to move to R-comps, the car started breaking from the stress of competition. I have now retired it.
So I started working on driving the Z. I didn't buy good tires for the Z until I had learned to drive it on street tires and did some mods aimed at Time Attack. I ended up in SM2 with no power-adders. After 5 years of having a car that's PAX-crippled for one reason or another, I think I'd like to try to compete with a car that's actually competitive, even though it means de-tuning the brakes and final drive to fit into SP.
I looked at my PAX scores in SM and compared them to what they would be in BSP. Even with cording 710's and minimal engine tweaking, I came in 5th. I believe 4 of the guys ahead of me are National level drivers. So now maybe you see where I'm going with this. I want to see if I have learned anything, and would like to compare apples to apples

 

With upgraded tuning (e.g. replacement computer, which IIRC, is legal in SP classes) a different exhaust will have a benefit beyond weight savings since you can tune for the new exhaust instead of the OEM.

BSP is a big hill, but after seeing first350's do incredibly well this year, I think that the Z just might be very competitive there.

 

^+1 on what he posted. With the right aftermarket exhaust system, you can gain HP with the proper tune, along with the weight saving benefits. Dual exhaust is much more favorable than single canisters as far as weigh savings. I went with the INJEN SES, coupled with a Magnaflow x-pipe muffler (cut down on the drone & regain some of the lost torque from being a true dual). It's been a couple of years since I installed it but I believe there was a 30+ lbs reduction in weight.

NOTE: Depending on what Region you're in and what mods you have, the Z can be competitive in BSP. I took 1st in BSP in 2007 with a couple of local clubs. Unfortunately, I installed body braces (more for road course than autocross) and now I'm in SM2, where I'm getting my *** handed to me by FI Miatas & S2Ks.

 

Personally, I wouldn't want to have a 50# delta from the rear of the car.

 

its worth going to a single 3 inch...i remove the spare and tools from my car before i go out and autox it and it doesnt make my rear end dance around like a fairy. Evo's dominate BSP and they have 60/40 weight distribution so all this 'balance' crap is blown out of proportion IMO, it has a huge effect in Formula cars and what not but in a 3300 pound street car the effects are minimal. you can always dial out a little front weight bias with sways/shocks anyway. if it really bothers ya that much you can get headers/test pipes/flywheel that will drop weight off the front of the car and even things out a bit, and a Cusco/Nismo LSD will also put some more weight back there to even things up.

 

One of the reasons that I have not replaced my exhaust in stock!

However, I think that you should be able to pull 50 pounds out of the front by changing the intake and exhaust headers (and other changes as well), which may very well balance out removing the 50 pounds of muffler.

 

Weight savings is always of benefit regardless of how it affects balance.

If you're prepping your 350Z to the limits of BSP rules then the exhaust is of huge importance to take advantage of the full Motec M800 ECU with launch control, custom intake and full length headers, max legal overbore, max legal head shave, etc.

 

I'm with John on this one. IF your going to be in BSP...you might as well run every mod you can to stay competitive. What ever class you are in, run with as many of the mods they'll allow as you can

 

you can run Motec in BSP?

 

"15.1 D.
Alternate computer control modules may be used whenever an equivalent change to the conventional system is allowed. For example, alternate computer module control of ignition settings or fuel injection is allowed."
2007 SCCA Solo Rules

That means my UTEC would be allowed. I just don't want to spend the money on guages, UEGO, and tuning to install it. Then again, I could truly tune the engine for my mods and atmosphere if I kept it. For the money, I think it would be better to trade it for the Technosquare reflash and exhaust. Budget constraints are a factor. I would be looking at a minimum of about $300 extra to either pay for tuning or buy a wideband and EGT guage and install everything. Worth the extra money?

 

That depends entirely on your budget, and priorities.

 

In general this may be true, but if "balance" weren't important, then race teams wouldn't spend tons of time and $$$ working on the balance of the car.

My reasons for not replacing the OEM exhaust on my Z were because the rear is light already, so removing more weight would "transfer" too much weight to the front. Also, instead of 50 pounds down low, I would have to run a full fuel tank (vs. 3/8 tank) -- or about 60-70 pounds more fuel in the car (and higher in the car) in order to reduce wheelspin on corner exit. In addition, since I can't change the computer, I can't tune the engine for the exhaust (and a lot of people have noted little-to-negative gains for exhaust changes -- but they sound good!).

However, I agree with John on this -- if you want to be competitive nationally, you need to make all of the changes (that give you a benefit) within the rule. Locally (unless you run in the same region as the Barry's), you could probably be very competitive with fewer modifications.

 

Are you running an aftermarket LSD?

 

Balance is important, just not as important as weight reduction. As in your case, sometimes the rules get in the way and rearrange the priorities, but 99% of the time, weight is king.

 

I Am. Cusco RS.

 

Yes, Nismo GT LSD.
Another question- what part of the exhaust is really heavy? I could just replace the muffler with a Ti variety and probably save weight and money. BTW I have a small subwoofer mounted in the rear corner in the spare tire well, so losing a little weight wouldn't upset the balance that much. Despite my love for racing, I can't stand OEM stereos on the 29 days out of the month when I'm not on the track.
I have the leather heated/airbagged seats, too, so when it comes to losing weight, that's the first place to look. I estimate it would cost $2500 to do a budget safety setup, (seats, roll bar, harnesses) so that will have to wait until next year's budget is determined.
Nobody has addressed the noise issue. Maybe I should try the Exhaust Forum for that. There was a link somewhere or a magazine article that had the dB ratings of all the Z exhausts.

 

If you do the JIC exhaust, it will be very loud. Does changing the catalytic converter take you out of BSP?
A good and cheap setup would be the TurboXS exhaust with test pipes. Its not super loud, but it'll give you power. In exchange, you lose some weight, but not as much as you wouldve with JIC Ti.

The JIC Ti will be very very loud, believe me, I have it.