Trans-Dapt 2566 Swirl Torq.Spacer Gm99-00

Fits good bolts that come with it work. Have to grind the top of the fan shroud to make it fit no matter what. Doesn’t take too long. Barely whistles. Just note...do it when the engine is cold. The antifreeze line at the bottom of the throttle body will have to come off, will have to be extended by 2 inches...and it will leak antifreeze. Overall it’s not bad for the price. Noticed bottom end torque immediately. Fuel mileage is the same but I do idle a lot...

This is the second Trans-Dapt throttle body spacer I have installed. Both times the spacers did exactly what Trans-Dapt claims they will do. I installed this on my 2003 Chevy Silverado 5.3 V8. Before installing, I didn't feel a noticable jump in torque until I got above 4,000 rpms. Now torque starts taking off around 3,300 rpms and climbs from there. Since installing, my transmission doesn't downshift as often either. The increase in torque doesn't require the lower gear as much. I have not dyno tested, but seat of the pants tells me there is a noticeble increase in both torque and horsepower. The box says you can bolt on more horsepower in less than an hour. This is pretty accurate. I did have to trim the plastic fan shroud to allow for necessary clearance. Also, there is a coolant line running to and from the bottom of the throttle body that gave me a little difficulty while installing. Other than that, the instructions were crystal clear and easy to follow. I have yet to run a full tank of gas to determine mileage increase, but from past experience, the spacer will give a noticeable bump in mileage as well.Overall, this is an easy bolt on that pays for itself.

would of gave it 5 stars but there where a few fitment issues when installing as it didnt want to clear the upper radiator hose and the crossover hose had to be lengthened otherwise had noticeable torque after re-tuning the pcm great for towing or a lil more pick up off the line

Throttle response is better, but fuel mileage stayed the same. They said it doesn't whistle, but it most definitely does.

The Trans-Dapt 2566 Swirl Torq Spacer GM99-00 was delivered in appropriate packaging. The included instructions were not as clear as my experiences with similar but more expensive spacers. Being familiar with installation, the part was very easy to install. There is some whistle during acceleration, but not as loud as other spacers. There is some feeling of increased torque, but without being able to do a dyno test, I am not sure of the increase in power and performance, including any increase in gas mileage. However, for the relative low cost, compared to other brand names, I would recommend purchasing this over the brand names.

I've had this installed for about 2 months now, waited to write review till I got a feel of it. It says no whistle, that's a lie. 2004 Chevy Tahoe 5.3L, and it whistles occasionally. Now I don't mind it, but figured you should know.There is virtually zero gain in fuel economy, power, or torque. The one thing that this does that warrants it being ok, is I've noticed when starting from a stop and accelerating uphill, it's quicker. When going up a steep grade on the highway, the engine doesn't seem to downshift as much as before.Hope it helps.

If your buying this to help increase gas mileage then stop right here. From my experience, I actually lost about 1 mpg city and highway. But from a stop is where this thing shines. It takes a whole lot less pedal to get this beast moving, and requires a lot less pedal to keep it moving. If you tow or are just looking for a little more pop from a 5.3, here is your answer. Not a real pain, but it does not go right on there as the directions made it sound. Have a little patience, but still relatively painless for a D.I.Y. er.

It fits & definitely well made i jst cant tell if its do much but its affordable