The Feeling of Confidence & Control

spec plus v2 white

You’re here because you just inherited a Mustang.

Or maybe you’re about to pick up a classic to work on with your kids. Maybe you’ve had a car sitting in the garage under a cover and you’d like to get it out again. Whatever the situation is, you have trouble trusting the car. It’s twitchy, it wanders around the highway, the drive is harsh, the steering a little vague – everything about the car just feels… off.

These are the types of complaints we’ve heard from countless Mustang owners, even those who have spent thousands on all new parts only to have the car feel worse than it did when they started. This is how those cars end up in the garage, covered and forgotten.

That’s why we built on Spec+ Package. It’s a group of parts, a recipe if you will, to help build confidence, control and trust in these old cars. Repeatedly tested and loved, our goal is to get you back on the road with a complete system that works together to deliver a feeling.

Now make no mistake, this is not our “base” package. It’s not a mixture of crappy parts we threw together to make something “affordable” and try to get you to upgrade. No, this kit is composed of some of the best parts we’ve been able to source for a vintage Mustang with a few of our own touches to enhance drivability, stability, and handling. It’s not a race car kit. We would not recommend this setup if your goal is to dominate the local track scene. But if your goal is to dominate the local winery scene, or feel comfortable cruising to and from the mountains, this is the one you’re after (though we have seen this kit pull 1.1Gs in the turns).


We begin addressing the front suspension by replacing the upper control arm with a tubular replacement that we build in house. We design these arms to be slightly offset which improves positive caster, and we replace the mounted balljoint with a screw-in type, allowing for quick and easy serviceability down the road. We also spent a great deal of time focusing on the shaft that mounts our upper arm, making design improvements to the bushing, mounting points, and stops.

On the upper arm we mount a typical rubber spring perch (rubber rocks, don’t let anyone tell you different) and install a set of 500lb springs and a shock that we helped personally develop from Bilstein.

We replace the lower arm with a stock option from Moog because, quite simply, it’s the best one we’ve found. We also replace the strut rod bushings with new rubber pieces from Moog that allow the strut rod to do it’s job.

We tie it all together with our 1 1/8″ sway bar.

    • MOD Upper Control Arms
    • 500lb Springs
    • Bilstein Front Shocks (Street Valving)
    • Rubber Spring Perches
    • Stock Replacement Lower Arms
    • 1 1/8″ Sway Bar
    • Replacement Strut Rod Bushings


We know that leaf springs can flex side to side by as much as 2 inches. In a sharp turn (like when avoiding something in the road) they flex out and suddenly snap back. This feeling is hard to describe, other than “I don’t like that.” So our goal is to create stability, and a positive feeling in the rear of the car when you need it most.

We start with our proprietary leaf spring. Leaf springs get a bum rap, mostly because the ones on the market today are typically constructed of the lowest quality steel in a design that hasn’t been touched in 50+ years. So we went back to the drawing board and came up with a design that improves lateral control, minimizes wheel hop (even on high horsepower applications), and utilizes an unusual mix of bushings to improve ride quality. We then back this up with a set of Bilstein shocks. Simple and effective.

    • MOD 1 Rear Suspension Kit


If you’ve ever tried parking one of these cars without power steering, you know just how essential it is. But finding the right combination of pieces is a daunting task. Our focus started with the proper steering geometry, a bunch of math that helps tell us engineers how natural the steering is going to feel. After all, it shouldn’t take 13 turns of the wheel to turn a corner, nor should it take half a turn to make a u-turn.

So we start by replacing the steering box with a high quality ABS unit with a 14:1 ratio. We back that up with a KRC Power Steering pump, the likes of which can be found on everything from street rods to race cars. From there we source quality replacement components: center link, tie rod adjusters, and inner and outer tie rods. Again, focusing on the best stock replacements we can find, not the ones from the discount bin.

    • MOD 1 Power Steering Kit
    • Replacement Centerlink
    • Replacement Tie Rod Adjusters
    • Replacement Tie Rods (Inner and Outer)


You don’t want 4 wheel disc brakes. Period. It took us several years of research to understand the chain of events that drives people to make poor decisions with their entire brake system and it all starts with the belief that for safety’s sake, you have to have disc brakes in the rear.

Here’s the deal: the rear axle flexes. It flexes a lot. I don’t care if you have a Currie unit from a Sherman tank, the rear axles will flex. This has the effect of pushing the rotors (which are mounted to the axles) around within the caliper. So instead of having the pads gently riding the rotor, there’s a gap. This gap has to be filled when pushing the brake, which makes the whole system feel inconsistent and scary.

So what do guys do? They buy a bigger master (which moves more fluid at a lower pressure, resulting in even worse brake feel), they back it up with a brake booster (don’t get me started) and then they start asking about firewall reinforcements because they have to put so much effort into the brake pedal.

Keep your drums in the rear. Unlike disc brakes, drum brakes shoes don’t get pushed around by the drum. That means a gap is never created. Plus the rear brakes only account for maybe 30% of overall braking because there’s just so little weight back there compared to the front. We always encourage customers to keep their drum setup (even on some of our racier applications) and spend the extra money on a great set of front disc brakes like the Wilwood Dynapro 6 Brake kit.

This is a 6 piston caliper, but not “because race car”, but because the new 6 piston designs more effectively manage brake pad wear. Couple this with an upgraded brake pad and a tandem master cylinder and you’ll have a system that stops on a dime and gives you back 9 cents in change.

    • MOD 1 Front Brake Kit (including all new big pin spindles)

From: $8,022.88


64-73 Mustang MOD Tubular Upper A-Arms

The MOD Upper Control Arm was designed to replace the stock piece in your early Mustang while improving strength and serviceability, resulting in a more predictable and confidence-inspiring ride.


64-73 Mustang 500lb Coil Spring

This 500lb coil spring has been used as the baseline for performance suspensions for 1964-1973 Mustangs for decades now and is a perfect replacement in stock applications.

64-70 Mustang Front Bilstein Shocks × 2

Mustang Bilstein front shocks provide a great dampener at an affordable price and are tuned specifically to the early model Mustang. Sold in pairs.


1964-1973 Mustang Spring Perch

Replace your worn out spring perch and spring perch bushings with a fresh set.  Goes along great with a new pair of vintage Mustang upper control arms.

Sold in pairs.


1964-1973 Mustang Stock Lower Control Arm

For the person who is not quite ready to go to a fully adjustable tubular lower control arm we offer the tried and true factory replacement Mustang stock lower control arm.

64-73 Mustang MOD Front Sway Bar

The Mustang front sway bar kit is a great step to getting your early model Mustang to handle.

64-73 Mustang MOD Front Brake Kit

Our MOD Front Brake Kit includes everything you need to get your car stopping like it should. Based on years of firsthand experience, we've found this combination of parts to deliver the feel most customers are looking for on the street and autocross (with seldom track use).

64-73 Mustang MOD 1 Rear Suspension Kit

The Mustang MOD1 Rear Suspension package is an upgrade that every vintage Mustang needs.  The MOD1 kit was designed with simplicity in mind.

This Kit Includes:

  • MOD 165# Leaf Springs
  • Our updated Panhard Rod Kit (found here) with Optional Adjustable Sway Bar (not recommended for street-only cars)
  • Bilstein Rear Shocks
  • MOD Leaf Spring Plates
  • Polyurethane Front Eyelet Bushings
  • Rubber Shackle Kit
  • 7/16″ U-Bolts
  • Lowering Blocks (Optional-Recommended for 1964.5-1966 Mustangs)

64-70 Mustang MOD 1 Power Steering Kit

This kit will increase the predictability and control of your car, simplify future part replacement, prevent power steering fluid from being blown on the engine, maintain proper steering geometry, and increase the enjoyment of your driving experience.

DRP Hub Bearing Spacer

Bearing spacers are a significant upgrade that improves wheel spin by over 1200% while improving the longevity of your wheel bearings. When properly installed they will provide an immediate increase in hub free spin, an improvement large enough to feel just by pushing the car around.

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This entire kit can be installed in a garage with typical hand tools. Many of the parts are fairly easier to swap in and out. Some, like the steering, will require you to remove other parts before accessing the ones to be replaced. We recommend professional installation if you are uncomfortable with the idea of replacing your brakes and steering systems.

This package will require the adaptation of your current brake lines to your new master cylinder.

No welding is required.

Be VERY careful when removing and installing new springs. They hurt, ask us how we know.

Leaf Spring Installation Instructions

Power Steering Installation Instructions

Dynapro 6 Installation Instructions