I've been poking around looking at an exhaust system for my MR for a while now and one thing has led to another such that I now have a Mine's titanium straight converter pro (70mm diam). Right now, however, I am looking for the rest of the system and from here stems my question:

How important is it to match the size of the pipes in an exhaust system? Should I go for the Greddy PE Ti (70mm = 2.75"), Fujitsubo RM-01ATi (76.3mm = 3"), Fujitsubo Super Ti (80mm = 3.15")?

The stock down pipe is only about 60mm (2.36") in any case and I think the stock CAT is about the same size. Is there any problem with going from a smaller pipe to a much larger one?

Is there a science to all this? With my DC5, I've had several different configurations and it seems that bigger flow = more top end power/pants low end, while more restriction is virtually the other way around.

Can anyone shed any light on exhaust tuning?

p.s. I'm new here, if that's not obvious. If there's a thread that covers this already, my search failed to reveal it. I'd appreciate anyone pointing this out.

 

Different sizes in the exhaust system can cause turbulence in the exhaust flow, get the exhaust with almost the same diameter from DP, highflow cat and cat-back.

 

https://www.evolutionm.net/forums/sh...ad.php?t=99023

 

Plain and simple, if you do 3" all the way back, you should be all set.
Buschur himself even recommends it, if you really want to make power for the Evo. This would be beneficial throughout the powerband. Some people claim they lose some low end torque from the 3" piping, but then you gain in the midrange and high end powerband. So, I'll stick to the 3" all the way.

Right now, I have a 3" catback and my Evo feels strong all-around. I'm still waiting on the weather to install the 3" downpipe and the highflow cat, and those should really make some more power. I decided on the HF cat cause I don't really like to smell fumes and deal with CELs, BUT test pipes releases alot of power, but, it's loud.

Last thing... if you were going to change out your exhaust sytem... start from the end back to front(turbo). I don't think it's a good idea to have a 3" downpipe and have the oem cat and catback....bottlenecks.

 

Depends on what you want in a long run for the car. If you are going for big hp from big turbo, difinitely go with the 3" tbe, but if you are sticking with the stock turbo, a 2.5" tbe is all you need.

 

Humm... the concensus seems to be on the 3". But if you use a 3" cat-back does the change between the small exit of the cat and the large opening of the pipe make funny noises?

What's the general view on continuous pipes? I mean there are pipes without joints better than ones with? So much so that it's worth the money?

Anyway, I'm going with the RM-01A type Ti (3", no joint, yes it's bloody long) and a Fujitsubo downpipe (2.75"). Once I finally get in installed, I'll probebly stick somehthing on the exhaust thread.

Keep on truckin'