What is the correct gap if any,also was intrested in fastman tb I have a 05 dat with magnaflow exoust and aem intake will the tb help with gains over stock also if i install headers which kind jba gibson anyone have expirience with either and do i have to replace the stock cat with a high flow unit if yes what kind having problems finding info figured this was the place to ask thanks.

 

First...welcome to the site, lots of help and knowledge here. Several people try different parts and combos and share the intel.
In the upper section of third gen forum there is a 05-07 Dakota service manual, its a pdf and is loaded with info(including the plugs). Rec saving a copy to your comp.
there is also a great search eng in the header area. you can narrow it to the third gen dak to help.

V8 is .40 gap
Fastman will get a little HP/TQ (upto 10 maybe) but best part isthe improved throttle responce, great product.
Haven't tried the headers yet but I know someone on here has and posted pics with it (use the search eng )I think they wee the JBA
The Y connector is the most restrictive area, change that before investing in headers.
Supedak has done alot of eng mods so he is a good source for answers, you can always PM him using the inbox feature.

 

what do you mean change the y connection i put on magnaflows dual catback is this locatd before the cat

 

are you running true duals all the way from each manifold?
Stock our trucks have two cats, one in each pipe running from the manifolds that the join in a Y pipe and then normally go through a single pipe system.
Most cat back systems start after the y connector and split out there to duals or high flow singles.

 

here is a pic of the y connector

[IMG]local://upfiles/57176/18023427E6D047FD8EE12D3F6CB8AC65.jpg[/IMG]

 

its from the cat back not from the manfolds

 

you can see in the pic how the pipes narrow to join, if spending more money on the system I would put a high flow Y pipe connector on before doing the headers. Remember that as you enlarge the flow you may move your HP/TQ curves higher in the power band loosing some lowend grunt, so don't oversize them.