Thanks Joshua for your help.
Perhaps you could push them for muffler only and varex only options for people like me that want to change the sound

Also, with the 3inch setup, did you get many issues with clearance to the body, etc of the car. Any knocks/rattles. Did you try it on any rough roads/rally etc?

I had no knocks or rattles from the exhaust. Fitment was good.
Clearance on the street was fine, but it did get rubbed on the ground when I was racing offroad.

I see the catbacks (2.5'' and 3") are on the xforce website!
Are prices available yet?
They've also got EL headers on there too!

Yes, head over to the classifieds section here.

Is there still talk of a Varex verion?

There is, but it's all just talk ATM. No firm dates or details.

Here's the results from my dyno testing of some exhaust options.

The 3" XForce cat-back made 2.5% more torque and 2.2% more power.
The 2.5" XForce system (high flow cat pipe and cat-back) made 4% more torque and 3.2% more power.
For reference the Borla cat-back made 2.5% more torque and 2.2% more power.
The Borla UEL header with the XForce 2.5" system made 6.74% more torque and 5.4% more power.
The 86Drift race header with the XForce 2.5" system made 9.07% more torque and 5.32% more power.

Now for some weights. I used bathroom scales so accuracy isn't great.
Stock:
Cat-back 18.3kg
Cat pipe 5.6kg
Header 9.5kg

3" XForce
Cat-back 20.1kg
Cat pipe 3.8kg (not used in dyno testing)

2.5" XForce
Cat-back 22.3kg (heavy tips installed)
Cat pipe 3.7kg

Borla
Cat-back 12.7kg

86Drift
Race Header 5.4kg

Volume from loudest to quietest
Borla
3" XForce
2.5" XForce

Dyno Graphs

XForce 3" cat-back.
http://imageshack.us/a/img14/7779/3inchcatback.jpg

XForce 2.5" cat-back and high flow cat pipe.
http://imageshack.us/a/img707/5983/2...backandcat.jpg

Borla cat-back.
http://imageshack.us/a/img836/732/borlacatback.jpg

Borla UEL header and XForce 2.5" exhaust.
http://imageshack.us/a/img837/6807/b...d25xforcee.jpg

86Drift race header and XForce 2.5" exhaust.
http://imageshack.us/a/img32/1251/ra...25xforceex.jpg

Combined results.
http://imageshack.us/a/img28/4599/allplot.jpg

Summary
The Borla and 3" Xforce cat-backs made the same power. The Borla is a lot lighter but is much louder. The XForce 3" cat-back is $180 cheaper.

The headers were tested with the 2.5" XForce exhaust because it is much quieter than the Borla and 3" cat-backs.
This is important because without a cat in the header the volume is much higher (I didn't take any db readings).
The Borla UEL header made the most torque in the dip, but the 86Drift headers made the most either side of the dip.
It was fairly even up to near the redline where the 86drift headers took over again.

Thanks for the info!
Sounds like the xforce 2.5" is the way to go.

Xforce 2.5" is the way to go if you plan on installing cat-less headers. BTW, if you want to avoid a CEL with cat-less headers you can use one of
these. I've had one of my car for months with no CEL.

If you just want a bit more volume and a nice sound, the 3" cat-back is a good option.

If all you care about is weight and don't mind it being loud, then the Borla cat-back is for you.

I think I might just go with a 3", considering the wait for the 2.5.
A little concerned about the volume, but I guess the 3'' would have a bit of a deeper note to it? Which would be a good thing with the uel headers!
Also, what's the 3'' system like with drone?

I didn't try it with the UEL headers so I can't be certain how loud it will be.
The 3" does give a deeper note.
I didn't notice any drone.

Could you please find out what the ground clearance is for the 3" system at stock ride height? I don't want to risk any rubbing having lowered my car 1.25"...

When the next person gets the 3" cat-back I'll try and get the measurement.
I had it on my car when it was lowered about 40mm and it didn't scrape, unlike the front bumper!

Ill be getting the 3" in 2 weeks so ill let you know