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my friend just purchased an 84 n/a and it is in need of a new exhaust from the cat back. What have some of you done to replace this and how did you like your results and also what have you paid

thanks
ryan
 

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I went to a 2 1/2" pipe from the header and got rid of the CAT!!! The muffler itself was just one step above a stock. Down here it only cost $300.00 including the pipe, muffler, hangars and chrome tip. As for results, well "Lil Red" idles smoother and sounds alot better too. However, don't forget to do something with the air intake also.
 

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On an N/A you are doing it for the sound and the feel, not the performance. A nice basic intake and exhaust upgrade/setup on an N/A will only yeild you something like 7HP at the max. For the same price you could buy a junked turbo and do the turbo swap for a cool 40HP!
 

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What stu85na said is correct, there is only a small gain from exhuast alone. Best way is to go to a local muffler shop and have them custom make a system for your car. You'll want a 2.5 inch pipe. Now you'll want to ask for mandrel bends in the pipe which will cost more. Back before I knew much I got a crushed bent system for 165 out the door. That included pipe, dynomax super turbo muffler, dual tips, tax, labor. Now crushed bent is what most people run but mandrel is better. If you want to know why do a google search, but essentialy mandrel flows better due to symetrical flow around a bend. Mandrel will cost you a bit more money, probably 200-250. Now if your friend is all about performance spend the extra and get mandrel if he just wants some extra power, doesn't expect to do much with the car, and wants sound just get a crushed bent system. Since we are talking about such a low amount of hp gain the difference between the two systems won't really be seen.
 

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Yup, buy an exhaust for looks and sound on an NA, performance isnt going to differ much between them. And I would NOT remove the cat on an NA.
 

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dont remove the cat..cops dont like it...and 280 the difference between mandrel and bent is quite significant..mandrel is (simply) a pipe rolled for bending instead of just straight up bending it.. rolling the pipe results in a 2.5 in (2.5 pipe) corner...no loss in width of piping on the curve..bent piping will result in a smaller diameter pipe around throughtout the bend in the pipe..taking the piping down to 2inches or 1.75 inches instead of the 2.5 you think youre paying for..it is cheaper tho..dont be cheap tho
 

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I know what the difference is 17_6 but on a 300zx n/a there isn't going to be much of a difference in power gains between a mandrel bent or crushed bent. Also a 2.5 inch crushed bent gets dropped to between a 2-2.25, it's not as big of a drop as some people make it out to seem. Thats again another reason there isn't much of a difference, becuase on a stock or close to stock 300zx n/a a 2.25 inch pipe with less bends than stock is going to flow better. Also there was an article in import tuner or similar magazine a couple years back where they tested a 240sx with stock , crushed bent w/increased diameter pipe, and mandrel same increase in pipe. The dyno test between the crushed bent and mandrel was about 1hp. Of course this was on a stock 240sx so who knows what the difference would be on a nicely modded one but we all know that when it comes to the 300zx n/a it's not going to make much power no matter what you do.
 

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well this is depending on the severity of bends dont say it sould drop only 1/4 in not knowing the bend...a 45 degree bend may drop .5 in or more...either way...you want more hp and then make it worth it in the long run...its not worth doin mods and have the exhaust bottle neck the power...simple as that
 

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Well in my estimation of what should happen in a crushed bent exhuast system I looked at my 84 300zx, my 77 280z, my friends 94 mazda truck, and friends 91 t-bird. While the degree of the bend does come into play even on a 90 degree bend of a 3 inch pipe it only dropped to just above 2.5 inch. On a 2.25 inch exhuast with a 90 degree bend it dropped to just above 2.0. So thats less than .5 inch on a 3 inch exhuast and less than .25 inch on a 2.25 inch exhuast which leads me to believe a 2.5 inch exhuast would have a drop of somewhere between .25-.5. Thats why I said it would drop to somewhere between 2.0-2.25. Also I do agree that if you want the max performance you should get madrel bent which is what I said but I also stated that if the guy wasn't planning on doing much with the car then there wasn't any need to spend the extra cash on the mandrel bent piping considering we are only talking 5 or less hp. I would be willing to bet that a 300zx n/a with a crushed bent vs a mandrel bent wouldn't be any different on the track unless it was highly moddified. Same goes for a dyno. Also as has been mentioned before the bottle neck of the 300zx isn't the exhuast but rather the intake manifold and head. Since most people never go that far with mods why spring for the extra 50-100 dollars for the mandrel bent that on a stock or close to stock car will only yeild a 1, maybe 2hp, gain. You can't even feel that kind of difference. To each their own I guess but personaly I'm leaving my 300zx exhuast crushed bent, now my 280z on the other hand will be getting a mandrel bent this summer becuase it's actually worth it.
 

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yes ok..ill agree mostly there and in the end...more mods on crushed vs mods with mandrel..the hp adds up more...but yes exhaust is another restriction to the z...for sure...and fuel with the turbo mods...only good for round 270ish then youve lost just bout all capacity..either way...if youre cheap and dont care go for crushed..yes thats it
 
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