Subaru swap exhaust tube size

[tjet]

Question for you guys that have done a EJ25 or EZ30 swap:

What size tubing is coming from the head to the collector, then on to the muffler?

I'm planning out the exhaust for my ER27 H6 swap.

Thanks

[tjet]

Here's a shot of the Subaru ER27 exhaust ports compared to a 2.1 WBX

[BCgee]

My somewhat relevant experience is a complete SVX 3.3 exhaust replacement last Fall 2019.

I purchased the SmallCar custom SVX header and used their SVX custom flanges, then built the remaining system from MagnaFlow parts and stock tubing with a local welder. If memory serves the primary and secondary pipes on the header were 1 5/8 to 1 3/4, whereas the latter exhaust system and mandrel bends were all 2 1/4.

Hopefully others who've designed their own exhausts from headers to muffler will chime-in.
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1987 SVX Syncro Hightop

[wesitarz]

An aftermarket EBay Subaru 2.5 header shows 1.5 to 2.25. I have a Smallcar header that I think is 1.5 to 2, since it uses the stock Vanagon J-pipe and I use a stock Vanagon 2 inch cat connected directly to it.