The 240SX/Silvia is an amazing platform in all it s generations. The FR-Drive-train and it s light weight offer a perfect balance between speed and agility. Used in a wide range of motor-sports such as drag, drift, autocross, road race and even rally the 240SX has proven it s worth time and time again. As a street car, it s refined and well mannered, comfortable to drive in and stylish with a bit of aggression in it s curves. Although it s initial design was sporty and aggressive it was still designed as a street car. Those who seek the most from their car know that in the rigors of competition you need to extract every ounce of performance from your machine. You need the capability to have every degree of adjustment above and beyond that of a street driven vehicle. You need the strength to withstands the stresses and strains of hard corners, a rough course and brutal weight transfer and chassis flex. It is within this understanding that Megan Racing has unveiled our line of reinforced suspension arms that offer the strength and adjustment that any competition vehicle will ever need. Constructed of high-strength steel alloys that offer durability, strength and yet remain light-weight, these control arms have been track tested for months in road race, autocross and drift events to assure quality and performance. These Roll-Center adapters are installed to correct suspension geometry after a car has been lowered. The uneven length of suspension arms causes Toe adjustments to occur drastically during braking suspension "squat", these Roll-Center Adjusters make up for the travel in the suspension arms to return suspension geometry to it's correct starting point. This allows alignment and steering to remain more consistent and predictable during aggressive driving and competition. ROLL CENTER INFORMATION: Front roll center is determined by the angle of the lower control arms and the angle of the upper strut mounting points. These angles, drawn in space, determine the instant centers for the front suspension (instant centers are the points that the entire suspension moves around during body roll). Then take a line from each instant center to the middle of the tire tread on the opposite side, and where these lines intersect, there is your roll center. Rear roll center is determined by the use of the angles of the upper and lower control arms to determine the instant centers of the suspension. Then, just like the front, take a line from each instant center to the middle of the tire tread on the opposite sides. The intersection is your roll center. Roll center angles must be measured from pivot point to pivot point. Modifying merely the angle of the arm doesn't do anything at all. Most of the "RCA" ball joints don't do anything besides move your arms closer to the ground. [RCA description credit to Andrew Adriance] NOTE: Due to the complexity of the installation, professional installation is REQUIRED! Application: 1989-1994 Nissan 240SX/180SX/Silvia (S13)