After reading this post

It seems that lots of people don't know much about what each downpipe kit offers.

I've been collecting information (pre-purchase research) and this is what I've found so far.

***Any corrections to my information are appreciated.***

I just want to have everyone on the same page.

I've put each option against a list of features that seem to cover a portion of each aftermarket downpipe system.

Those features are:

1. Increased pipe diameter over stock?
2. Removal of Pre-Cats?
3. O2 sensor location fore and after cat?
(this will allow ANY ECU to run with the downpipes)
4. Test-Pipe Option?
5. Flex Joints?
6. Cat Type
7. Cost?

So now how does each option (that I'm aware of) stack up?

Stock System
Diameter = <2.25" (I believe)
Pre-Cats = YES
O2 Sensor location fore and aft of cats = YES
Test Pipes = NO
Flex Joints = YES (metal mesh/bellows-type)
Cat Type = Pre = Metal, Main = Ceramic
Cost = Nothing, you already have them.

APR
Diameter = 2.5" (I believe)
Pre-Cats = NO
O2 Sensor location fore and aft of cats = NO
Test Pipes = YES
Flex Joints = YES (metal mesh/bellows-type)
Cat Type = ?
Cost = $1600

AWE
Diameter = taper from 3" to 2.5"
Pre-Cats = NO
02 Sensor location fore and aft of cats = YES
Test Pipes = YES
Flex Joints = YES (ball/socket joint)
Cat Type = 400 cell per inch Ceramic Matrix
Cost = $1595

JP Engineering
Diameter = taper from 3" to 2.5"
Pre-Cats = NO
O2 Sensor location fore and aft of cats = YES
Test Pipes = NO
Flex Joints = YES (metal mesh/bellows-type)
Cat Type = Carsound (400cpi Ceramic)
Cost = $1350

Milltek
Diameter = 2.3" (60mm)
Pre-Cats = NO
O2 Sensor Location fore and aft of cats = They say YES, but it doesn't look like it from the PICS. But we'll go with YES since they claim it.
Test Pipes = NO
Flex Joints = YES (metal mesh/bellows-type)
Cat Type = continuous stainless steel cores
Cost = $1865

MTM
Diameter = ?
Pre-Cats = NO
O2 Sensor location fore and aft of cats = ?
Test Pipes = ?
Flex Joints = YES (not sure what type)
Cat Type = ?
Cost = $6900 (part of there Stage 3 package)

RS4
Diameter = ?
Pre-Cats = YES
O2 Sensor location fore and aft of cats = YES
Test Pipes = NO
Flex Joints = YES (metal mesh/bellows-type)
Cat Type = ?
Cost = $3000
(cost is from this post

That about sums it up.

Corrections are encouraged (after all, we should all know the right information).

I'm not trying to start a war (or am I?), just trying to get the cold hard numbers.

Can one of you RS4 downpipe junkies post information about the pipes, I know nothing about these.

FWIW...