performance gains from larger mid pipe?

[MSP#735]

ok so i already have the 2.5" dp with high flow cat and im gonna install a 2.5" mid pipe and the 03 muffler........has there been a noticable amount of difference when doin the mid pipe?

 

[FC3s Boy]

you notice it, and even more once you go with a larger cat back

 

[Mr. Win]

turbos dont like back pressure... the more open the better.

 

[FSDET]

you notice it, and even more once you go with a larger cat back

i think by midpipe he means cat back cuz he had a high flow cat on the down pipe.

 

[MSP#735]

i think by midpipe he means cat back cuz he had a high flow cat on the down pipe.

exactly....i was just curious as to what kind of gains to expect or lack there of...gonna do it within the next few days (rockon)

 

[jmc94gsx]

When you start to modify your exhaust start with the back then work towards the turbo, therefore getting a downpipe before a catback is absolutely pointless.

 

[MSP#735]

too late......lol

 

[spacemonkey]

I was wondering the same thing...stock muffler/catback cant be that bad.

I dont really want a loud exhaust...or an N1 muffler. I want something close to stock looking. Like Greddy EVO or SP2

Must be some kind of gain since th biggest restriction is the twin inline cats

 

[Bhamsan]

When you start to modify your exhaust start with the back then work towards the turbo, therefore getting a downpipe before a catback is absolutely pointless.

I'd have to disagree with this. Someone quoted corky bell on this saying that if theres going to be a bottleneck anywhere, its better to be in the front than the back. I'm not a physicist or anything, but that makes more sense to me. Even when I installed an apex DP I had before, I felt a lot more gains from than than with just a catback.

If I knew exactly where someone posted the above mentioned information, I'll show you the link.

 

[biochembruin]

the exhaust gas starts to cool, and takes up less volume the further it is from the engine.

 

[Puckpimp71]

yupyup That's why you want more space in the hottest areas, at least from what I've experienced.
There's some reasoning to the contrary, however. I read on a DSM site that it may be better to go bigger as you head towards the rear of the car because the exhaust right out of the manifold is hottest and therefore moving faster, so a smaller pipe will rush it out the back more quickly, then get bigger as the exhaust cools to reduce backpressure. I could see how that makes sense on NA cars, but even then, I don't entirely agree with it. Back pressure or lack of it is something that can be tuned for. There was an SHO guy that put true dual 3in exhaust from the headers back on his 3.0l V6. Most people claimed that there'd be loss of power, but with the ECU properly set he got some good gains.

 

[jmc94gsx]

Bhasman: You've got to be kidding me, you start with the back first, look at any at the performance "stages" that Supras and DSM's have traditionally used and you will see the same trend. YOu start with the back first. Think of the extreme opposite then, a set of performance cams would be absolutely useless with a stock exhaust setup.
I remember the first thing Dave Buschur recommended for my exhaust, catback and testpipe, those were my first mods and they will be for any turboed car, real life tesimony, it simply works and has been 1000's of times over and there is no need to be overanalytical.

 

[spacemonkey]

You start with Downpipe 1st...look at what Curcuit Sport did with there project MSP. They said the most restricting part of the car is the twin inline cats. I still think the DP is more important then our cat back. You will get better gains gutting or changing the cats to highflow.

 

[jurgs01]

You only do the DP first if you are sticking with the same size piping as the cat-back. Otherwise you would bottlneck flow by having a larger mid-pipe than cat-back.

 

[spacemonkey]

Thats true but the twin inline cats are a worse flow restriction then different size piping...im confident the gaines are bigger with just DP rather then just Cat Back. Of course Cat back and DP is the best combo.

I think 2.5 inch is good enough for my goals.

Modern day cars usually gain more HP from a ECU reflash due to stricter emissons. Cats have to last XxX,XXX miles. Thus the biggest killer of cats is hot (temp) exhaust gas (next to rich)...to combat this cars are made rich...especiallt rubo and rotary cars since Exhaust gas is noticably hotter then NA. Atleast thats what I read on what Mazda did to the RX-8. As for the reason for the 2 inline cats I dont know...I do know they are the biggest flow restriction on these cars.

 

[JDM Sam]

Bhasman: You've got to be kidding me, you start with the back first, look at any at the performance "stages" that Supras and DSM's have traditionally used and you will see the same trend. YOu start with the back first. Think of the extreme opposite then, a set of performance cams would be absolutely useless with a stock exhaust setup.
I remember the first thing Dave Buschur recommended for my exhaust, catback and testpipe, those were my first mods and they will be for any turboed car, real life tesimony, it simply works and has been 1000's of times over and there is no need to be overanalytical.

The MSP isn't a DSM. Different cars respond to differently to mods.
You gain very little with a catback first on a MSP. Do a search on the OG members of the forum with dyno sheets to prove. Damn NOOBs.

Wassup to all the early 2003 people.
(cheers) (drinks)

 

[t3ase]

The MSP isn't a DSM. Different cars respond to differently to mods.
You gain very little with a catback first on a MSP. Do a search on the OG members of the forum with dyno sheets to prove. Damn NOOBs.

Wassup to all the early 2003 people.
(cheers) (drinks)

You gain very little with a catback alone, that is true. You need to work from the turbo -> back for maximum gain.

The stock S-pipe is killer. If you're one to tinker and don't mind loud noises, try this.. Try unhooking the downpipe only from the exhaust. It's a simple 5 bolts. That alone will prove to you the difference.

OG, WHAT?@!$#!@

 

[Bhamsan]

It took me a whole day to read responses, but like JDM Sam said, this car isn't a DSM, and obviously you don't know anything about the MSP at all. The gains from putting on a DP are so great that you can feel it from just driving around, whereas putting a catback on the MSP has yielded very little gains. If you owned a MSP and worked on one at all, then maybe you would, but obviously you haven't.

 

[spacemonkey]

Stock

VS

Not Stock:

 

[Swerny]

It took me a whole day to read responses, but like JDM Sam said, this car isn't a DSM, and obviously you don't know anything about the MSP at all. The gains from putting on a DP are so great that you can feel it from just driving around, whereas putting a catback on the MSP has yielded very little gains. If you owned a MSP and worked on one at all, then maybe you would, but obviously you haven't.

W3RD!
I have had a bunch of exhausts and combos on my MSP and the Apex downpipe/midpipe alone made a huge difference by itself, and it's catted.
A bunch of people here have said that adding a catback to the stock front end did nothing power wise (including Tekkie who has the 3 inch Thermal catback).
The SP2 i'm waiting for might help a bit top end, but it will be more of a sound/looks/weight savings mod than performance IMHO.