If you want deep throaty sound, your going to need headers, rockers, or better yet, a CAM.

All of which they don't make for the 3.5L

One of the worst motors to have, as it doesn't have any aftermarket support.

Yeah, I'm starting to regret buying something with such a limited aftermarket. Do you know where I could get a custom cam cut? I mean, there have to be machine shops that do stuff like that.

A good engine building shop could probably hook you up. I'm sure if you dropped the car off with them they could study your engine and make something for it no problem.

Only thing is, one off engine parts are NOT cheap. Where I pay $1000 for a cam, you'll probably pay close to $10,000 for one. See where I'm going?

Also, that 3.5L is not a bad motor stock. It'* some gitty-up behind.

I owned a 99 3.5L intrigue and it was my baby. I wooped on v6 mustangs all day with that 215hp engine.