Rep Power: 243

ok... the exhaust ports coming off the head are about 1 1/4 in diameter... which means its about 3.9 inch circumfrance.... so... with no bottlenecks in the system that would mean that running off the head... it would be 3.9 inch circumfrance.

the headers that they make run in that area....

Stock: 4in.
Megan: 5.5in.
HP: 5.25in.

i also know that the dc is close to the stock manifold... but i dunt know what the outlet on the headfer is... does anyone know or can take measurements of the outlet on their headers???

i've done some research... i no it yields minimal gains... but i like to do things differently like most people...(as i say with my tranny laying on my table downstairs with the gears out)

the stock one is best as it seems to run off the head the best... but the other are performance which means they have either longer runs of piping instead of a 4-1 application... i dunt see how putting a 5 inch tube up to a 4 inch inlet would help.... but i understand the idea of the longer runners... my question is this tho... im keeping my stock cat....

i want the straight piping of the head to meat correctly with the header... aka... 4 inch to about 4 inch... but i want a larger exhaust port from the head... where it starts to run under the car... because thats where i believe the bottleneck is... beyond that... i will run new tubing around probly and put on a new exhaust.....

anyone have any ideas...

 
Rep Power: 389

Hmm, you lost me right on that last paragraph.

Your a smart dude, but I must mention that you need to keep in mind you NEED backpressure in your exhaust system.

Based strictly on your numbers, I'd probably test the HP header and what it gives. From what I remember, the EX downpipe is what - 2.5 or 3 inches. If you planning on running another inch diam for the downpipe--- wait, are we sitll using circumfrance numbers?

Bust out the paint program would you?

 
Rep Power: 0

Outlet on the stock header is this:

ID: 53mm (2.0866 inches)
OD: 56mm (2.205 inches)

 
Rep Power: 243

hey... thanx very much man

 
Rep Power: 0

No probs. Let me know if you need any other measurements. I have a head off the car, but its ported and polished so the measurements off that won't do you much good.