Does a JET Throttle Body Spacer for the GM 4.2L Engine Help/Hinder Performance?


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These kinds of "After-Market Whiz-Bang" Products always draw Equal Measures of Love and Hate Reactions from "The Great Unwashed"... The VOX POPULI... You know... "The Voice of The People".. But hopefully... the BEST reactions come mostly from the People who actually HAVE tried out these types of devices. Not surprisingly,,, this subject will also draw out reactions from the People Who Have NOT tried them Out..

Nonetheless, even in the absence of having Real Proof, Actual Data, Personal Knowledge or any Provable Hands-On Experience... this latter group will have very entrenched views and take positions about the subject matter anyway. This Device seems to be one of those trivial, nebulous mechanical trinkets that acts like a "Bright and Shiney Object" drawing attention and concern from BOTH sides of the matter.

But consider this to be a Rare Instance involving our GMT-360 I-6 Vehicles AND the use of one of these Purpose Built "trinkets" ... and Let's see what THIS Trailblazer Owner's impressions turned out to be after he actually purchased, installed and tested out this device by driving his vehicle around enough to make an honest, empirical assessment with his Before and After Performance Comparisons::



Without a real dyno test, his butt-o-meter doesn't count. He's just encountering a placebo effect or he's getting kickbacks from Jet. He's also getting some cash with the 1.4M views he's had. Even CAI's have been PROVEN to be BS so how can this even do anything.

I totally call BS.


No actual dyno numbers means there is no empirical evidence. Throttle bosy spacers are good for drilling and tapping a feed line for N2O usage however 😁


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(+) Column: 0.5
(-) Column: 2.5
(+) Bonus Pts: 0.5 (Have to admire JET for including that Cool Bracket)
Last edited:


I have tried them on a couple other fuel injected vehicles years back. Wasted my money.

When he had to remove the cold air intake and it has a junk K&N filter I realized he may be brand guy, since the cai are proven to do nothing and the filter allows more dirt into the engine.

He has no real data at all. It was far more like a sales pitch than an actual attempt to prove anything legit.

"I think" he has nothing but his thoughts. I also hear the same kind of comments from people that waste money on 93 octane on our trucks cause they want to feel it has an effect when it won't unless tuned for it.

I do respect that he admits it is not worth it even though you can watch him trying so hard to justify any improvement.


Well-Known Member
A different thought of the topic. These would be very cheap to produce if you needed, say a million or so, it would only add $20 or so to sticker price. Or they could have just designed the original TB little longer. If they made any real difference in mpg, I believe GM would have made them standard on vehicles, since all auto makers were and are currently trying to meet higher mpg standards.
Although, I sometimes question the last sentence. 1984 chevette, carb, automatic, always driven like I stole it. 32 mpg

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