iam looking at getting underpullies and headers... it will probobly cost me 550 plus shipping, How much HP gain am i looking at.
I have a K&N cold air intake, with a 93 diablo tune. I have a flowmaster muffler but need to know what i can do to get the most out of my money. I am not looking to rev my car harder, just HP. i want my engine working easier, not harder!!! any ideas!!!

 

Neither one really give you that much power, header have showed no gain on N/A cars and very small on the F/I cars. These 4.0 breath pretty well form the factory, the bottleneck is from the heads on the output side.
UDP's show minimal gain but you will see some, 4-7 HP maybe. for the money is it worth it?
If you wanna feel more power go with gears, t-lock and LCA's. Put some more of that power to the ground instead of going to waste. It will really help.
GOOD LUCK.

 

Haha, HP the only important thing??? I agree with ron, Get the gears

 

how much are you looking at with new gears, ive been wanting to do the headers and pullies but, the gears sound like more for your money... what would the best set of gears be for the 05 v6 mustang with intake and exhaust? my car runs a 9.5 in the 1/8 mile but is slow off the line... are they hard to install or would i prolly need to have someone do it for me?

 

You'd have to find a reputable shop to do gears or headers. You could probably manage the headers on your own or with a friend, but its a pain in the *** and it would be best if done by a shop. The gears have to be done by a shop unless you've done gears numerous times before. Good luck.

 

If you are going to do gears you might as well put a t-lok or other limited slip in there as well to save yourself some money on installation charges.