BA I6 Exhaust Sizing... What are your thoughts ?

For nearly 10yr's i have taken great joy in changing zorst's on my falcon...

2.5" to 3" to 4" back to 3" and finally my first ever stainless system now back to 2.5"

I ran my best ET with 3"

I ran my best mph with 3"

I made my highest dyno number with a 3"

So why change you may wonder ?

For too many years I have debated I'm right everyone else is wrong when I have tried new ideas on my car's and I never did get that elusive 12sec timeslip no matter how many tuners I visited...

I think I'm getting older and regardless of how modified this turd is I still need to be mindful of my neighbors and bolting on a quieter system may go some way to stop them from ringing the police on me when I get home at 4am lol.

For anyone interested I am going back on the dyno shortly to get a torque graph for comparison reasons.

Not interested in racing this anymore it's more a show car now and of course I may change my mind in the future but for now it is about being a sedate mature motorist.

A lot of guys have gone from smaller to larger and to my knowledge no one has gone back down in size for any reason ?

So I am super keen to see if my bumometer is still accurate and i will post my findings later in the week .

I couldn't find an exhaust related thread anywhere so I stuck this in here, admin please feel free to move.

Cheers Daz

The factory diameter (for a turbo model at least) is 2.5" I think, but not sure what the N/A version was. 2.5" should be fine for most street applications, but if you are chasing HP and torque, particularly in the mid to upper range I would have thought the 3" to 3.5" system would be more suitable. Being a considerate neighbor is important, so instead of buying a whole new cat back system I personally would have ingestigated bimodal insert options for your 3" so you can close a valve to make the exhaust quite on-demand. That way everyone is happy. This is just an example and may not be suitable for your car, but food for thought

https://jhp.com.au/wp-content/upload...with-Kit-1.jpg

My thoughts exactly - a bimodal muffler or a similar operating system somewhere in the pipe so you can still be civil to your neighbours but literally open the taps when you.., err, open the taps.

I had a motorbike with a muffler like this, used to open at around 6000rpm (also roughly when the 'shower' injectors kicked in) and the bastard used to go mental. I loved it!

Well I went X-Force...

All the hwy drone has disappeared and the Torque definitely feels like it has improved even tho the car is heaps quieter

Win win :)