Exhaust diameter recommendations?

[benzino]

Just wondering what size exhaust i should go when i do my swap.
I can get vectra headers but they have a 2" outlet and i was hoping to go 2.25". But maybe i should just go 2" seeing as though the resonator and muffler i have are both 2" and then go 2.25" just on the cat to remove some of the restriction there.

So yeah, anyone got info about optimal size for the 2.0?
Also is the stock lanos exhaust 1.5" or 1.75"?

Cheers mates

[daewooluvr]

Lanos stock is 1.75" in the US

[gse_turbo]

go with the 2", I used 2.5" and it sucks. it's too loud and it has a crappy tone.

[benzino]

Thanks guys.
So even with a 2" it will free it up compared to stock.

[gse_turbo]

yeah, and think about the components, thats were the biggest help comes from.

[benzino]

well i have a 2" hot dog resonator and a 2" inlet 3" outlet dogleg muffler and i was going to go 2.25" ceramic cat
Do you know much about header tuning garrett? Also you have a pm

[gse_turbo]

the 2.25 cat is fine, you'll just want to keep with the 2.0 pipe befor and after.

as for the header tuning, I built a REALLY awsome header for my 1.6and I think I went a little too big for the somewhat low stock CR. I used 1.625" primaries and 2.0" secondaries into a 2.5" exhaust. I think 2.0"-2.25" exhaust would be best, 1.75" secondaries and 1.5" primaries. that being said, this may just be the case with the 1.6 with it's smaller bore and stroke. I still think the smaller setup is best for the 2.0 however. these motors don't rev up high enough or have large enough intake ports to need anything bigger.

[gse_turbo]

I'll get back to on that PM this afternoon.

[benzino]

well the two header options i have are:
Pri ID- 1.49"
Sec ID- 1.73"
Outlet- 2"
or
Pri- 1.65"
Sec- 1.77"
Out- 2"

the first one is nearly exactly what you said

i have an exhaust tuning excel spreadsheet (from the docs section of this site) but i think it's only really useful if you're building your own. the sizes it has calculated for peak torque are pretty close to the 1st one too (just a little smaller ID)