Need help deciding exhaust diameter

[terry_em1]

I have an EM1 with the factory B16A2. Currently its stock and it will be for a good while. The plan is to swap out the intake and exhaust for parts that will help the engine breathe better. Bonus would be losing weight.

I'm stuck between 2.25" and 2.5" exhaust system. Whats on the car now is a stock manifold, stock cat, and this Longlife muffler. I do have a Toyosports manifold, but it has a 2" outlet, which I think its too small. I decided to sell it.

Whats your opinion? I'm new to B-series, so I could use some advice ha. Whatever size you think suits best, can you recommend some manifolds? I am planning to get a custom centre section made, with V bands and an universal muffler.

 

[xxxencorexxx]

2.5" manifold, if going 4-1 bear in mind it will hang lower, 4-2-1 will have better clearance
2.5" exhaust

Good to go

 

[Pete180]

Most people go with a 2.5" system and have good results. It future proofs yourself for further mods especially if you're doing intake stuff too. That's what I went with myself on my em1 but I am b18 now. My brothers b16 has a 2.25" system on his and honestly it feels really pokey, I dunno if its the back pressure or something but it feels torquey for what it is.

 

[terry_em1]

Most people go with a 2.5" system and have good results. It future proofs yourself for further mods especially if you're doing intake stuff too. That's what I went with myself on my em1 but I am b18 now. My brothers b16 has a 2.25" system on his and honestly it feels really pokey, I dunno if its the back pressure or something but it feels torquey for what it is.

You make a fair point. Better to do it once than twice.