Modernizing GM’s Most Iconic Platforms.

Powertrain conversions, chassis modernization, wiring, fabrication, and complete project execution.

Specializing in 1988–2006 GM cars, trucks, and SUVs.

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TOTAL VEHICLE CUSTOMIZATION & PERFORMANCE

Sunday Spec builds comprehensive customization and modernization projects for select GM enthusiast vehicles. Our primary focus is 1988–2006 platforms, including OBS and NBS trucks and SUVs, third- and fourth-generation Camaros and Firebirds, C4 and C5 Corvettes, and other carefully selected GM vehicles.

We coordinate the complete project around how the vehicle should perform, drive, function, and feel. Capabilities include:

  • Engine and transmission conversions
  • Powertrain upgrades and supporting systems
  • Custom fabrication and wiring
  • Cooling, fuel, and electrical integration
  • Chassis, suspension, steering, and braking upgrades
  • Complete vehicle planning and project execution
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COMPLETE MODERNIZATION FOR GM's ENTHUSIAST VEHICLES

A well-modernized vehicle should be more enjoyable every time you drive it—not only faster. Sunday Spec improves the systems that affect comfort, confidence, safety, usability, and overall driving experience while preserving the character that makes the vehicle special.

Modernization upgrades may include:

  • LED exterior and interior lighting
  • Apple CarPlay and modern audio integration
  • Backup cameras, dash cameras, and parking aids
  • Improved ride quality, handling, and steering feel
  • Brake-system upgrades and modernization
  • Cooling, charging, and electrical improvements
  • Gauges, controls, accessories, and convenience features
  • Wheels, tires, and fitment selected for the vehicle’s intended use

Each project is planned as a complete package so the powertrain, chassis, electronics, and driver experience work together rather than feeling like unrelated modifications.

OUR CAPABILITIES

  • ENGINE & POWERTRAIN CONVERSIONS

    Engine swaps, transmission conversions, driveline upgrades, engine management, and the supporting systems required to make the combination perform reliably.

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  • CUSTOM FABRICATION

    Purpose-built exhaust systems, mounting solutions, brackets, chassis modifications, intake systems, turbocharger systems, and other fabricated components tailored to the vehicle and project.

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  • WIRING & VEHICLE CONTROL INTEGRATION

    Engine management, standalone controls, gauges, body-system integration, accessory wiring, and troubleshooting between original and modern electronics.

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  • CHASSIS, SUSPENSION, & BRAKING

    Suspension conversions, steering upgrades, brake systems, chassis reinforcement, and supporting modifications designed to improve stance, control, safety, and overall vehicle performance.

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  • PROJECT PLANNING & BUILD MANAGEMENT

    We help define the scope, organize priorities, source components, coordinate sequencing, and manage the project from initial concept through final assembly and testing.

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SPECIALTY SERVICES COORDINATED THROUGH TRUSTED PARTNERS

Some projects require capabilities beyond what Sunday Spec performs in-house. When needed, we can help coordinate select specialty services through trusted providers so the project remains organized and the finished vehicle stays aligned with the original plan.

These partnered services may include:

  • Paint and bodywork
  • Vehicle wraps, paint protection film, and window tinting
  • Custom upholstery and interior work
  • Engine machining and specialty machine work
  • Powder coating, plating, and finishing
  • Alignment, calibration, and other specialized services

FEATURED PROJECT

Sean Parker's 2000 Pontiac Trans Am

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OUR PROJECT PROCESS

Custom projects are easier when the next step is clear. Here’s how we take the conversation from first idea to finished work and long-term support.

  • Phase 1: Consultation & Vehicle Review

    We start with discussing your vehicle, goals, budget, and how you plan to use the car. For older vehicles, previously modified cars, or larger projects, we may need to review the vehicle in person to understand its current condition before making recommendations.

  • Phase 2: Estimate, Deposit & Parts Planning

    Once the direction and goals are clear, we prepare the estimate, collect the deposit, and begin sourcing the parts needed for the project. This step helps lock in the plan, timeline, and components before the vehicle arrives.

  • Phase 3: Drop-Off, Installation & Setup

    When your scheduled drop-off date comes, your vehicle will arrive to our Alpharetta facility for installation, setup, tuning, fitment, or custom work. We keep you in the loop every step of the way with weekly updates and progress pictures through our communication systems.

  • Phase 4: Delivery, Walkthrough & Support

    During delivery, we walk you through the work performed, answer questions, and help you understand how to care for the vehicle moving forward. After the build, we stay available for follow-up, maintenance, adjustments, and future upgrades.

BUILT WITH CONFIDENCE

Sunday Spec supports every custom project with clear scopes, documented approvals, regular communication, and a 12-month workmanship warranty.

ABOUT SUNDAY SPEC
12-Month Workmanship Warranty

All packages and custom projects are guaranteed by a 12-month warranty on our workmanship.

Written Scopes & Approvals

Project scope, changes, and major decisions are documented and approved before work proceeds.

Communication Throughout the Project

Customers receive clear updates as the project moves through planning, fabrication, installation, and testing.

Post-Delivery Support

We remain available after delivery to answer questions, address concerns, and support the finished vehicle.