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JB1 to JB4 Upgrade Kit
JB1 to JB4 Upgrade Kit
JB1 to JB4 Upgrade Kit
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JB1 to JB4 Upgrade Kit

Marsoni M251S
Sale price$175.00
Pay 4 payments of $43.75 a month.Shop Pay
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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  • 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
4.3 ★★★★★
Based on 1851 reviews
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Product Reviews
D
Verified Purchase
Dennis Stalzer
Birmingham, US
★★★★★ 4
Nice looking watch with day and date
Color: A5 - Black
This watch has a nice black face and looks like it is high quality considering the price. I guess time will tell how durable it is. The only thing I am not as pleased about is the band which is stiff and is not as comfortable as another watch that has a leather band.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on January 18, 2026
S
Verified Purchase
Sunflower
Dallas, US
★★★★★ 5
A stylish watch at a moderate price
Color: B1 - Gold / Brown
This wrist watch is stylish and at a modest price. The watch was given as a gift 🎁
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on December 4, 2025
L
Verified Purchase
Lisa Ahrensbach
Lake Worth, US
★★★★★ 5
Durable. And no batteries required.
Color: A2 - Black / Brown
Best watch I've ever used. No batteries needed.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 19, 2026
A
Verified Purchase
Amazon Customer
Fort Morgan, US
★★★★★ 1
Watch stopped working within 2 months.
Color: A1 - Blue / Brown
Purchased this watch on July 23, 2025. It stopped working on September 17, 2025. Watch looks great, but it is a piece of junk. Recommendation is do not purchase.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on September 18, 2025
A
Verified Purchase
Amazon Customer
Belleville, US
★★★★★ 5
Very nice father gift
Color: A4 - Blue / Black
Very nice, exactly looks like the picture, comes to you very fast, no long wait for you package, I got this for my dad and he was very happy and satisfied. Recommend this product.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on April 17, 2026

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