Long Tube Headers 1-5/8 or 1-3/4?

[MikeysOTP]

My car is NA now, but I hope to add a twin screw in the future. Should I go with the smaller primaries now to avoid loss of low end power, or should I suffer now in order to have the larger diameter when I go FI? I am leaning towards the 1-5/8 but I wan to know if anyone else has been through this. I will be running on the stock internals with the supercharger so I would assume that I will be able to reach the limits of the motor regardless of which headers I use.

 

[o0Dan0o]

Kinda depends, the 1-5/8" will be much better than your stock manifolds for the FI, probably a more significant increase than between the 1-5/8" and 1-3/4". While the larger headers will be better for FI, I think it would take ported heads to really take advantage. I'm not sure if the 1-3/4" come with 2-1/2 or 3" collectors.

If you know 100% for sure that you will end up FI, then I would go with the 1-3/4", but if you're iffy on it at all I would go with the 1-5/8". Better the something that you know you will use than something you think you might in my book.
Dan

 

[kooldawg6]

I agree.
1 5/8 if N/A or not sure about F/I.
1 3/4 if you will be going F/I in the somewhat near future.