Header and manifold Thread

[donmega]

think im going to go with the speed daddys

[rmcardle3]

That seems to be the most popular conclusion and the one I came to 3 days ago when I ordered my Speed Daddys.

I need and want 2 things.

1. I need to get by emissions testing done for an inspection sticker in Houston (P0420).
I know...., the c@ is the "most overly replaced item in the context of the P0420 code", so I did the following:

No Mods (well cone intake) just saying.
Had a few random P0301, P0303, P0306.

New plugs, 8mm wires.
Cleared the misfires (only temporarily).
Checked cleaned the one persistent misfire on P0303.
Vacuum at cruise is 15 Hg.
Did not have the Hg for the idle bench mark but 15 Hg sounds like a LOW idle bench mark for a GTP doesn't it?

My OverDrive cruising RPM has been gradually rising over time from 1200 RPM to now almost 2000 RPM. I get better mileage at 1200 RPM, 30 MPH, 31 MPG than now at 2000 RPM, 65 MPH, 24 MPG
(what used to be 1200 RPM, 65MPH, 31 MPG)

Increased back pressure at higher speeds?

I am thinking direct fit CAT MAG23405 for the inspection sticker, P0420, persistent misfire; low vacuum @ idle 15 Hg, declining mileage at higher speeds.
To address possible increasing back pressure?

http://www.performancepeddler.com/detail.asp?PRODUCT_ID=MAG23405


Next (only when done with 1.) .................... On to the Speed Daddy install.
2. I want to install the new Speed Daddy 3 inch "header, down pipe" in such a way that minimizes labor/welding transitioning back bone stock
(as /if needed).

I am thinking 3 inch high flow catalytic converter universal fit suggested here for my Speed Daddy 3 inch "header" and "down pipe" setup:

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=280452848347&ssPageNam e=STRK:MEWAX:IT

I was thinking "keep" the resonator to tone it down or does that just sound retarded?

I will post details as available. Comments welcome. Thanks