can someone explain to me underdrive pulleys? i read somewhere you can expect a 7-8 hp gain so I had them installed however now i'm reading that theyre not good for everyday driving?

 

you need to reset the ECU= look in the passenger footwell for a fusebox- pull CLOCK fuse for a minute and put back in place. Now the car can learn its new powerband from the pully change
The crank pully frees up about 8 hp that the sheer weight of the stock pully keeps locked in the engine 11 pounds versus less than 2 pounds
the other pullies are just bling and of no real value on a TL

The only concern is at idle with MORE than 600 watt stereo- the alternator isnt going fast enough (with the underdrive rpm) to power the system fully
You may notice the a/c not as good at idle too- but works fine on freeway or at any speed- again slightly less rpm to the unit at idle....

 

which pulley is the one right next to the engine? the most obvious one when you pop the hood? what are accessory pulleys for?

 

What pulley are you talking about?? The only pulley to spend money on is the Crank pulley. The rest are just for looks. (Alternator, Power steering) Our cars dont have harmonic balancers so what you have probably read online doesnt apply to us and they dont effect or damage our motors. Like tom said above the only thing you may run into is large stereos the underdrive pulley isnt good for that, BUT you can get a light weight stock sized pulley and wont have any thing to worry about.

 

I just had my underdrive pulley installed today and I was amazed at the improved throttle response. The engine just doesn't need to work as hard anymore.

 

I think he means the one right on top, in plain sight.

 

The one on top near the back side of the engine bay is the power steering pulley.

 

yup, that was the one i was talking about.. i was just curious to see what it was