i went to the track yesterday with full intentions of running some high 14 second passes.since my previous best was 15.1 and i have since added pacesetter mid tubes and a new y pipe with 2 40 series fm's and dual's i expected at least a few tenths gain.instead my first pass was 15.5 and i ran twice more getting 15.8 both times.the only reason i didnt go home totally unhappy is that i ran a chevy 5.3 the first two runs and beat him,and a dodge hemi ram that looked identical to mine except for his chrome wheels.he claimed it was completly stock but when we left the starting line his tires lit up in smoke,which was fine because i hooked up and left him there.it may have been his tires,but his "stock"exhaust note was louder than mine.lol.

I would guess that the headers leaned out your air/fuel ratio. Either that or they started to and the computer overcompensated by richening it up too much. In either case I think you'll find the cure in a different tune that takes headers into account. It really sucks to put something on the truck to go faster and end up slowing down!

How long had your headers been on before taking it to the track? The computer needs time to learn. Also changes in weather temp and humidity make huge differences.

quote:

The computer needs time to learn

My guess is that it's the weather. After my header swap I did the same thing. Like 2 days after I got my headers on I went to the track, high 70s and humid. I only ran .07 better than I did a month or 2 before without headers but it was about 50 and dry.

And I haven't been to the track in over a year so I don't really know how the weather affects 1/4 mile, but before my headers the best I could run 0-60 was 7 flat on a cold night. Now on a cold night I can run 5 flat but in 70+ and humid the best I can pull off is about low to mid 6 second 0-60s. The weather makes a huge difference in our trucks

yeah,you guys may be right about the weather,my origional runs were in 60 degree weather.this time it was mid 70's and humid.as far as my computer having time to learn my headers,its been like 3 or 4 weeks.i know ill be faster next time though my zex will be hooked up by then.

was the weather change that made you go slower

thanks dline,i hope so,id hate to think im spending all this money and losing ground lol.by the way i was drooling over those j&m heads,i just didnt have the bucks.how are your new heads 6.1 s arnt they?give you a good boost?

you get better flow with the headers but your choking it with the flowcrapers, get a set of straight through mufflers and you will see

I'd bet that a set headers with a set of true dual flowmasters flow better than a set of the same headers with a Y pipe and a single muffler.

So I don't think the flowmasters are his problem

I am sure realistically you are going to gain a couple tenths like you expected. But, in addition, just think of the cosmetic upgrade it provides.....

quote:

Originally posted by Starchief_59:
I'd bet that a set headers with a set of true dual flowmasters flow better than a set of the same headers with a Y pipe and a single muffler.

So I don't think the flowmasters are his problem

from the flow tests i've seen you need 4 Flowmasters to flow as much as a single Dymomax ultra Flo.
http://www.dynomax.com/news/Downloads/SEMA-Flowv2.doc

what is your intake setup? you need to make sure you match that exhaust with a good flowin cai...