Just came across this post and your results are interesting. I wonder if you added some flowmaster 50's or something similar to your setup and see if you would gain anymore power

 

Well an update to this is that i got an offer for a second hand X-Force cat back i couldn't refuse and so popped it on. I modified the front of the exhaust to mate up to the modified primary / cats, and wowsers it actually made a huge difference...

I haven't had it dynoed since, but yep, significant. Lights tyres when it never used to, and the sound doesn't hurt either, its transformed the car and seems to just breathe so much more easily now. Thoroughly happy!

For those like me who (# would love to) cant spend $3,000 AUD on headers, the primary widening trick is a great option.

 

Hey Sparky booked in for a tune and primary cat opened up at Sonny,s next Monday already got Xforce,hps and K&N should be good I will let you know cheers.

 

Hey mate, awesome news you will be blown away..

Thats exactly going to be my setup when you have tuned, so i can guess what my X-Force will have gained me based on your results! Great news!

 

Any drone with the X-Force?

 

None to speak of, maybe for a split second around the 1200 rpm mark. But that's being pretty bloody picky..