Price: $40.00
Pros: INCREASE OF TOURQUE
Cons: NONE
Recommended? Yes

Comments: NOTICED AN INCREASE OF THROTTLE RESPONCE AND ITS SWEET LOOKING

Price: $40.00
Pros: none
Cons: better
Recommended? Yes

Comments: more power

Price: $1.00
Pros: idk
Cons: idk
Recommended? No

Comments: im in vocational school for machine shop and was bored one day so i made a 1in spacer and i didnt notice any differences in power or gas mileage so save your money and buy something else

Price: $86.00
Pros: Works well on a 2.5L if you add a CAI and do the 4.0L TB mod.
Cons: No difference in performance unless 4.0L TB mod is done also
Recommended? Yes

Comments: I only did this inconjunction with the TB mod and the addition of a CAI. With these other mods there is a slight increase in performance and MPG

Price: $80.99
Pros: The heep pulls much better on hills w/ low RPM ranges. No changes to gas mileage or overall power.
Cons: It's 80 bucks :-)
Recommended? Yes

Comments: Simple installation. Done in my driveway after a night of 12 ounce curls. I felt like putting it on and didn't want to wait. There were no issues w/ installation and took me 20 minutes. I would recommend to others who live in mountainous areas. Probably not much benefit in flat areas.

Price: $30.00
Pros: Good
Cons: None
Recommended? No

Comments: Saw no improvement

Price: $68.00
Pros: Easy install and cheap
Cons: no
Recommended? Yes

Comments: A must for moving those underpowered 4 bangers! All mods should be carefully studied and priced.

Price: $70.00
Pros: Easy to install, high quality product.
Cons: None
Recommended? Yes

Comments: This is the first engine mod on my TJ. It really improved the mid range power. I used to down shift to make it up hills and now it will pull up the hill with out the need to down shift. I highly recommend for improved mid range power.

Price: $105.00
Pros: allows more air to the engine
Cons: n/a
Recommended? Yes

Comments: cheap upgrade that gives you 8hp or so

Price: $95.00
Pros: ?
Cons: ?
Recommended? No

Comments: not sure i really notice a difference in performance.

Price: $1.00
Pros: 1
Cons: 1
Recommended? Yes

Comments: 1

Price: $70.00
Pros: 
Cons: 
Recommended? Yes

Comments:

Price: $50.00
Pros: supposed to give better gas milage? i donno. cant tell. it whistles though... lol
Cons: nothing.
Recommended? Yes

Comments: it was cheap. so i thought i would give it a try

Price: $120.00
Pros: good power
Cons: gas mileage
Recommended? Yes

Comments: great product definatly recommend

Price: $90.00
Pros: Added suction
Cons: Not a huge difference, but noticable
Recommended? Yes

Comments: Definitely a difference, although not huge. Find a discounted spacer if you can

Price: $64.00
Pros: it makes a noticeable difference in low to mid range torque
Cons: it is a little loud sitting at lights
Recommended? Yes

Comments: It is a Power Aid throttle body spacer and took half an hour to install came with everything i need to install even a extra gasket for the throttle body. Doesn't effect gas mileage either positive or negative. this one doesn't have the high pitch noise when acceleration.

Price: $99.99
Pros: None, maybe the sound if you like that.
Cons: Waste of money
Recommended? Yes

Comments: This is for a '02 WJ w/ 4.7. The brackets provided were horrible, I had to make one piece myself. If I didn't spend 100 bucks, I would have thrown it away but I made it work. I don't think it did anything performance wise, it just whistles. Don't waste your money.

Price: $55.00
Pros: Includes all hardware for Wrangler or Cherokee auto or standard trans.
Cons: Available in the buff only
Recommended? Yes

Comments: New 2.5L,4.0L/4.6L stroker T-Body spacers. Bored to match the 63mm T-Body. Add to the flow, lower the torque curve by extending the distance between the intake valves and the throttle body(engineering!). The same as lengthening the intake runners for all the older motor heads.

Price: $35.00
Pros: Gave me more horse power
Cons: Still have to match the intake manifold size to match but not a problem with the product.
Recommended? Yes

Comments: Works great got it cheap and came with gaskets.

Price: $75.00
Recommended? Yes

Comments: No real notice...its a pretty good paper weight if you ask me haha. nothing crazy