2.5" downpipe vs. 3" downpipe

[Stewart, Joe (COX-Atlanta)]

>So, I am thinking of running 2.5" right off the turbo
>and then flare it out to 3". So, the downipe would be 2.5"
>for only about 1.5 feet.

I ran a very similar setup on my DSM. Good enough for almost 120 MPH in
the 1/4. You have to remember that exhaust gasses expand as they do so a
smaller diameter up front (turbine outlet) will not hurt you that much.
If you are very concerned you can wrap the first part to keep the heat
in.

Here is a pic of the downpipe I was running. It is 2.5" until the flex
where it flares up to a metric 3" size. It's about 1.5' like the one you
described.

http://nx2k.dynip.com/thumbs/assembling%20the%20gsx%20day%203%20web/page
s/DSCF0006.htm

If it makes you feel any better the muffler on this exhaust is a bit
less than 2.5", and I was still able to get this 3470 lb sled to 11.8 @
119.7 (backed up ET and MPH per NHRA standards, except for safety).

-Jay

PS 240 => sylvia conversion pics you posted look NICE