JB1 to JB4 Upgrade Kit

Marsoni

M251S

$175.00

Get it in 3 business days with 1 day shipping. Friday, May 29

JB1 to JB4 Upgrade KitUpgrades your existing BMS Stage1 to a EA888 JB4 BETA system. The JB4 BETA features CANbus connectivity for more advanced tuning, direct AFR control, advanced safety systems for boost, air fuel ratio, fuel trims, and engine knock, boost mapping by gear for improved traction, integrated water meth control, and much more. The upgrade kit cost is $125 outright. There is no longer a core exchange program available. After the upgrade you can keep your old

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Your JB1 to JB4 Upgrade Kit orders ship within 1-2 business days.

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Standard: 3-7 business days
Fast: 2-3 business days
Express: 1-2 business days

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Exchange/Return Notes

We offer a 30-day return/exchange service after receiving.
Final sale items are not eligible for returns or exchanges.
To process your return/exchange, please contact us at [email protected]
Please click here for more details>>> Return & Exchange Policy

I ended up going with another brand, which I returned because it was impossible to insert the batteries into the too-tight compartment (other reviewers had the same issue and I should have listened). So I bought this one and not only is the battery compartment ample size and easy to insert the batteries into, the company even sends you two AA batteries to start you off! I also very much appreciate the fact that you don't have to hold down the button, just push it once to start and push it again to stop. It's powerful and I love that it sits in its own stand and looks nice in my kitchen while doing so.

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Reviewed in the United States on May 29, 2026

Verified Purchase

Elaine

Chelsea, US

★★★★★ 5

Great quality, great price and works great !

Color: Flat Black

Works great ! Quick delivery and great price and I love that it comes with a cover !

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Reviewed in the United States on June 5, 2026

Verified Purchase

mnat

Phoenix, US

★★★★★ 5

Good idea great product

Color: Gloss Black

I bought this as a gift. The person loves it. It’s very compact. She puts it in her bag and travels with it. It’s easy because you can charge it at home and then it’s already. She sometimes brings her charger with her so she can use it out.

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Reviewed in the United States on June 1, 2026

Verified Purchase

Laura Van

Bozeman, US

★★★★★ 5

Works great.

Color: Gloss Black

We preferred this model because the button is on top of the unit, making it easier to use. And we do use it often. The battery lasts for a reasonable amount of time too, and charges quickly on USB.

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Reviewed in the United States on March 26, 2026