pipe diameter?

[Johny5]

I've been looking at all these exhaust posts and have been searching for quite awhile to find some info or feedback on the GP Sports spec d catback for a 98 240. The pipe dia is 80 mm on top of hks hipers 65 mm and I was wondering how much of a difference this will make on an na car. Future mods will most likely be at most a nice header and high flow cat. My main question is just, will I lose too much backpressure for a lightly tuned na motor with 80mm piping. And also, what is the build quality of GP Sports catback exhausts? Any help here is greatly appreciated.

[Johny5]

bump?

[Dousan_PG]

gp sports looks good quality
i'd go with it, its different, and relativelycheap iirc.


chill and wait for the RS*R ones too maybe. i waslooking at them a few nights ago. WOW. very nice. they open up in coming months


www.rs-r.com

peace

[Johny5]

http://www.rs-r.com/exmag_gt2.htm

oh my good lord :eek:

thanks for the heads up man, those rs*r's are really looking good.

[Dousan_PG]

they look MUCH nicer in person. very well built. also have the street series which is great for keeping it on the low down. you wont be disappointed when they come available (shortly)

[sykikchimp]

BACKPRESSURE IS BAD...

exhaust port scavaging due to high exhaust velocities is GOOD.

Backpressure has nothing to do with making power, and ONLY causes losses in power.

edit.. just looking through their site.. HOLY COW that ish looks nice!

I'm drooling:
RS*R iShock coilover system

Utilizing the Ti2000 springs, this coil over system will provide you the ultimate in suspension performance and tuning. With the ultimate suspension set up in mind, this coil over setup houses dual port 46mm pistons in an oil filled casing to which compression and rebound can be independently adjusted. As well as spring and shock height adjustment capabilities and upper pillow mounts for precision tuning that every racing enthusiast is looking for.

[Johny5]

I'm not saying too much backpressure is good, and I'm sure both do a good job at eliminating the backpressure stock exhaust makes. I'm worried about losing too much backpressure, which can cause a good deal of hp loss on an n/a car. All I wanna know is, does 80 mm cause you to lose too much backpressure? Is 65mm really the optimal width for my mods/future mods?

[Rennen]

dousan,

I assume you know someone that is associated with RS*R since you have a GAINT sticker on your car. I know that it will vary from dealer to dealer, but can you tell us a general price range for thier exausts. I am especially interested in the Ex-Mag series

-Matt

[misnomer]

Perhaps Dousan wasn't quite clear. . .

BACKPRESSURE IS BAD!!!!

Backpressure means your motor needs to expend more energy pushing exhaust gasses out of the pipe.

What IS good is high gas velocity. Essentially, if gasses are moving quickly through the pipe, the gas at the end of the pipe can help pull gasses out of the combustion chambers. Unfortunately, this is only gained by keeping the pipe diameter somewhat restricted (narrower pipe, gasses must have higher velocity to move the same volume), which tends to have the side effect of increasing backpressure. This is where the fallacy that some backpressure is good stems from.

Just remember: high gas velocity good, backpressure bad. High gas velocity gooooood, backpressure baaaaad. Repeat this five times.


<edit> I just reread and found I sounded kind of rude. I'm not a rude person. I'm a nice guy, there are other folks on here who get to play asshole. We get this a lot, don't feel bad :-)

[Dousan_PG]

Originally posted by Rennen
dousan,

I assume you know someone that is associated with RS*R since you have a GAINT sticker on your car. I know that it will vary from dealer to dealer, but can you tell us a general price range for thier exausts. I am especially interested in the Ex-Mag series

-Matt

i have no idea on price. i just was over there a few nights ago looking at the RS*R Supra an 350z. i am good friends with them. dont know pricing though, i have an idea but sworn to secrecy. im sure they will announce this month. espeicallly after the RS*R event. all ican say is that i LOVE that spring way instead of flanges. WHY? its more like a N1 and you wont have any exhaust leak worries. dont understsand

www.rs-r.com

under exmag II section. :) SWEET. ive heard the on a few cars already. BEAUTIFUL. VERY VERY NICE SOUNDING!!

i know a guy they tested it on FC, he said he LOVED IT
another on miata=enjoys the top end a lot
s14-sounds great
supra-very mellow and good power

i dont think pepole will be disappointted

BUT REMEMBER

RS*R AND INVIDIA ARE NOT ASSOCIATED WITH EACHOTHER!!

[240Degrees]

http://www.rs-r.com/exmag.htm

WOW this looks nice. this is the PERFECT exhaust ive been looking for. Looks like im not getting the Greddy SP.