Exhaust Suggestions?

[ljay103]

Ok, I have a 1991 Nissan 300zx Non-Turbo. The engine has about 80k miles and was swapped at roughly 100k miles (odometer reads 159k) before I purchased it. I'm the second owner of the vehicle since 2007 and JUST NOW starting to have time to work on it. Everything on the car WAS stock except for the amp, sub, and head unit.

Changes so far:
Jim Wolf Technology Intake
Flashed ECU (Flashed in 2007, going to reflash again after changes)
Eibach Lowering Springs
Strut Bar
HICAS Eliminator
KYB Shocks
AMS Short Shifter

So, I passed smog yesterday to register my vehicle. Here's the plan, feel free to comment or make suggestions on what you think I should do. I have already purchased Z1 Motorsports headers back in 2007 and haven't installed them yet. I wanted to get custom piping but wasn't sure if 2.5" or 3" diameter would be ideal. Again, this vehicle is a non-turbo. I believe the headers I do have are 2.5" in diameter. Since i'll be increasing the diameter of the exhaust, I would more than likely need to purchase 2 cats and 2 mufflers. I did have some questions for you guys and i'm sorry I have to give you the whole back story.

Questions about the headers?
- Lets say the headers I have are 2.0" or 2.25" will it hurt changing the piping to 2.5" or 3.0" following the headers or should I just buy new headers?

Questions about the exhaust?
- I don't plan to go underdrive or mess with the engine, just simple bolt-ons, what is the recommended diameter for an exhaust to maximize power?
- When I customize the piping will there be a use for Item #4? http://www.everythingnissan.com/300Zx-Parts-s/3.htm
- When I customize the piping, should I have the welder stick with the original bends or should they just minimize the piping distance to reach the muffler?

Questions about the cat-converter?
- Should I purchase the MagnaFlow universal converter? I'm not looking to pay $350 per cat.
- I've been to horsepowerfreaks.com looking for the converter but found that there are so many options. http://www.horsepowerfreaks.com/partdet ... ersal/9980 is it a single or a dual O2 boss? Built-in Resonated core?! Im totally confused.
- How many O2 sensor slots are there on EACH cat?

Questions about the mufflers?
- What would you recommend for mufflers? I hear the HKS is very nice!

LASTLY:
- Is horsepowerfreaks.com a fair price?
- Do you think i'll pass smog in California with these modifications?

***I REALLY APPRECIATE THE HELP IN ADVANCE. Sorry for my rookie knowledge!

[Ace2cool]

Buy a pre-made 2.5" system, unless your shop has a mandrel bending machine. Minimize bends. 3" is useless on an N/A. In CA pretty much everything is illegal. Terrible state to modify cars in. The cats will allow you to pass emissions. You want the 2.5" In/Out. No O2 bungs on the cats. The bungs go before the cats.

Personal recommendation, with you living in CA, just get a premade catback. HKS sounds nice on TT, but raspy on N/A. Plus I don't like the look of those melon launchers. B&B, Specialty Z, Labree, ect. would be my recommendation.

[ljay103]

Thanks Ace! I tried looking up the H-Pipes (http://www.z1motorsports.com/product_in ... ts_id=4634) for on 300zx.com and they are out of stock. I live in Nevada, but I don't want to have to mod it again if I decide to move back to California. On 300zx.com they have a HKS Hiper dual exhaust http://www.z1motorsports.com/product_in ... ucts_id=88 for $719+$60 shipping. Fair price? When i'm looking at the B&B Catback exhaust, they are asking about middle resonator? What do you think about that - need it or no?

If i'm passing smog now, do you think I should get new cats as well?

Thanks for your help!

[NolimitZ32]

Ok, I have a 1991 Nissan 300zx Non-Turbo. The engine has about 80k miles and was swapped at roughly 100k miles (odometer reads 159k) before I purchased it. I'm the second owner of the vehicle since 2007 and JUST NOW starting to have time to work on it. Everything on the car WAS stock except for the amp, sub, and head unit.

Changes so far:
Jim Wolf Technology Intake
Flashed ECU (Flashed in 2007, going to reflash again after changes)
Eibach Lowering Springs
Strut Bar
HICAS Eliminator
KYB Shocks
AMS Short Shifter

1. Um What^
2. AMS
3. Just like ACE said get premade and perhaps CARB approved (not sure if those exist for the Z32) system. Also getting power out of a NA is not impossible but EXTREMELY costly and requires more than just bolt-ons, if you're chasing power than you gotta go High Comp/High Rev or FI. Enjoy the Z as it is, make it a good looking comfy cruiser.

[ljay103]

1. "Um What^"????
2. Whats wrong with AMS? There a certain type that works better?
3. Looks like i'm going with the premade. To get another opinion, for an 'NA' would a B&B or HKS be better?

Thanks!

[NolimitZ32]

1. NAs never had HICAS, hence having a HICAS eliminator on a NA is impossible.
2. AMS (canada) is a scum company that steals innovators' ideas and markets them as their own. Their parts have terrible fitment and have in the past been cause for faliures (lots expensive, some catastrophic), their production is carried out entirely overseas (Chinese), their QA/QC is non-existant, and the owner is a complete prick who denies all of these things blatantly.
3. As I said before pulling power out of a NA is very difficult so it will make no noticeable difference as far as performance is concerned, this is a purely aesthetic decision which only you can make because the two are very different.

[ljay103]

1. So the HICAS elimantor bar I purchased and had put in pretty much didn't do anything for something it never had?! DAMMIT!

2. Even with the exhaust just being "aesthetic" i'm trying to pull as much HP as possible.

3. Would you say that the factsheet about installation of the pulleys increasing hp on this website is accurate (http://www.unorthodoxracing.com/pulleys/pulley-set-4786)? Although, I do understand that my electric stuff wont run right - I know the sub and amp will have to come out & AC is gonna suck. Not enough juice to run these things, especially in the triple digit temperature here in Las Vegas.

[NolimitZ32]

1. No you're not understanding, the HICAS portion of the TT is completely different from the NA rear end setup. It's impossible to install a HICAS eliminator on a car that doesn't have HICAS, so either your car was once a TT and got a NA swapped in (unlikely but some do this when they dont have the money for a TT after they've blown it up) or someone took you for a ride and laughed to the bank (sorry man but there are lots of mechanics like that).
2. Ok basically the difference in HP between those 2 exhausts will be <2 chp so it will come down to aesthetics.
3. Pulleys (and all rotational weight shedding) doesn't make extra HP it frees up available HP, once again it wont be enough to make a huge difference, you may notice the car rev a little easier but you will certainly not get anywhere near 28hp, i'd say you may see a 1 or 2 whp increase on a dyno if you're lucky.

I know these figures seem extremely low but the VG30DE loves boost, its a perfect engine for it but in it's NA state its pretty much maxed from the factory. NA upgrades are pretty worthless if you're searching for horsepower, I suggest you check out Honad's NA build thread, he's at something like 220 whp with every NA upgrade available (thousands of dollars worth).

[ljay103]

1. Thanks for the reality check...
2. Oh wow, didn't realize that. I figured I was gonna keep the cats and just buy a premade exhaust. So tell me if this is ok? Headers down to the cat will be 2.5" but the inlet and outlet of the cat look like its between 2.0" and 2.25". Route 1 - Would it be worth it to get a custom cat-back and keep the original working cats? Route 2 - Would it be better to change the whole thing meaning, get the catback exhaust, and 2 new hi-flow cats? If I did go with Route 2, what kind of cats would you recommend?

Thanks for letting me know about the increases. Looks like the best I can do with my NA is to just do the bolt-ons and leave it at that. I'll check out that thread you were mentioning. If not the horsepower, I hope these upgrades make my car run a little smoother, still a fun car to drive! Thanks for all your help!

[NolimitZ32]

I'd say get the headers and a catted exhaust to match (all pre-made), there is no point in spending the time and money to fab a custom exhaust with exception of a cat-back if there is a set of mufflers that you really like but that aren't already available for a Z32. I know I've seen some catted exhausts sold for the Z32, can't tell you what they are but I'm sure you'll find some options on Z1, SZ, and CZP. Don't really know about cats, never researched them my car is & has always been in Texas (not nearly as strict as Cali) and its TT swapped so cats went in the trash. Also best thing to do with a NA for performance is a good suspension setup and high quality powertrain/drivetrain components, basically you will benefit more from a lightweight driveshaft, pulleys, flywheel, and wheels than you will from a full exhaust because you will be unlocking power that's already there but being used to spin up heavy un-sprung mass rather than trying to pull more power out of the NA since its already pretty peaked. Before you go any further I suggest you read the "Everything you need to know about the Z32" Thread and "Destroying the world in your Z32" because these two have a plethora of information, likely more than you'll want to know

[ljay103]

Thanks for sharing some knowledge. I will check those threads as well. Very much appreciated.

[Ruber Ducky]

1. "Um What^"????
2. Whats wrong with AMS? There a certain type that works better?
3. Looks like i'm going with the premade. To get another opinion, for an 'NA' would a B&B or HKS be better?

Thanks!

Lol I had a short shifter as well for a day, didn't like it at all.

I have a 93 na with stock heads, if I remember right my downpipes are 2.7 from Megan racing. Then I went with B&B exhaust with a resonated x pipe at a 2.5 diamitor. There is a little backfire when I shift at lower rpms but it sounds boss and you do get a feeling of better response.

Like everyone else is saying though, if you want more power, save up for an engine swap.