Before you continue, please take a moment and read our legal disclaimer and the following information:


What our custom chip/programming will do, and what it will NOT do...

This question has come up quite a bit and we feel that it would be best to explain what you can expect from custom tuning before you spend any money with us, or anyone else.  Concerning a stock engine/drivetrain, a custom chip/pcm program is going to offer very little over the stock programming as far as performance is concerned, unless you have one of the newer systems (1988-up), in which case lowering the coolant fan turn-on temps, increasing top speed and rev limiters, or altering electronic transmission shift tables might help to some limited extent.  GM spends millions of dollars on stock tuning and they get the tuning much closer than anyone else can, concerning fuel delivery and spark advance; at least on a stock engine.  This is why most aftermarket drop-in replacements don't seem to translate into measurable gains at the track.

The point at which a custom program becomes a requirement is when you start to modify the engine, or swap a different engine or transmission into a vehicle that never came configured that way from the factory.  For example: upgrading the exhaust, induction, and/or cam will increase air flow which most computers cannot recognize.  Systems utilizing a Mass Air Flow sensor might be able to register this increased air flow, but in most cases they will only be able to increase fuel delivery and not alter the spark advance because of limitations in the stock programming.  Custom tuning can be tailored to your specific needs which will take full advantage of the modifications you have performed to your engine.  Also, if you have removed certain emissions control devices for off-road use such as the EGR valve, the EGR functions in the computer must be disabled at the same time or permanent engine damage could result.  If you have swapped in an engine from a different or newer car, it's EFI computer might require custom programming to run and perform correctly in the different car.  Custom tuning is a tricky business; no two cars are alike and every different vehicle requires a specific calibration to operate correctly.  Sometimes a "perfect tune" may not be attainable on the first try, but we are willing to work with you until you are satisfied within the terms/limits explained below.

All we ask is for you be patient with us during the custom tuning process.  That is one of the reasons why we price our custom tunes as low as we do; because it takes time tuning thru the mail and it requires the customer to participate in and contribute to this tuning process.  If for some reason you cannot be patient enough to work with us thru this process, then we suggest you either bring your car to us for in-person tuning or try to do the tuning yourself.


Additional Information and Notes:

All of the OBD1 (pre-1996) applications we support (except 94-95 LT1 flash) have a removable PROM or Mem-cal assembly, more commonly known as "the chip".  If you have a mem-cal or chip application, please ONLY SHIP US THE MEM-CAL/CHIP seperately (if required), not the whole computer.  There will be an additional charge for return shipping of computers.

If you are using a mem-cal (example), in most cases we will need to reprogram the OEM chip that is soldered to this mem-cal assembly.  This means you will need to remove the mem-cal from your computer and send it to us to be reprogrammed.  Your vehicle will be inoperable until you get the reprogrammed unit back.  If you cannot be without the use of your vehicle during this time, please notify us of this because an adapter might be available (at extra cost) that will allow you to hold on to your stock mem-cal and retain the use of your vehicle during this process.

Most 1980's GM computers did not use a mem-cal, but used a seperate PROM (example) instead.  In some cases we may already have your particular application on-file, and will be able to send you a custom chip without you having to send yours to us for reprogramming.  However, the OEM PROM chips are housed in a plastic carrier which will need to be transferred to my custom chip before you can install it into your computer.  Instructions on how to do this are located here.

All LT1 flash and OBDII PCMs must be shipped to us for reprogramming.  If you cannot be without the use of your vehicle during the time the computer is being worked on by us, please notify us and we may be able to make alternative arrangements.

Legal Disclaimer

You must be 18 years of age or older to enter into this tuning service agreement.  Prices subject to change at any time without notification.  All of our reprogrammed chips and/or PCMs are intended for OFF-ROAD / RACING USE ONLY in a vehicle that is to be used solely for competition. They cannot be used in vehicles that are operated on public streets, roads or highways. Their use is limited to closed-course and open-course racing that is sanctioned by a recognized racing organization.  Not all functions of the stock ECM / PCM are tunable using the software we have available, we will notify you if a certain request cannot be fulfilled.  The customer is responsible for obtaining scan-tool data upon request so we can accurately tune the vehicle.  Since most applications call for mail-order custom programming, we cannot be held responsible for any misapplication, miscalibration, and malfunction of custom programs.  Furthermore, we can NOT be held accountable for any other problems or faults that could exist in the customerís vehicle that this custom programming is intended to be used in.  Such existing faults could cause issues that would make it appear as though the custom programming is at fault.  Should this situation arise, please email us and we will make every reasonable effort to work with you thru the problem.  Data acquisition and the reporting of that data is the responsibility of the customer.  We will make every reasonable effort to make the custom programming work correctly with a customer's car.  The customer is responsible for ALL shipping charges and other fees.  Please allow a minimum of 5 business days turnaround time.  We cannot be held responsible for lost, stolen, damaged, or missing customer equipment or parts.  All returns must be approved via Return Authorization, contact us first for a return authorization before shipping your chip/pcm back!  Refunds will be given at our discretion only.  In order to receive a refund, all custom programmed devices must be returned to us so the original (factory) programming can be placed back on the device that was originally supplied with said device.  Shipping, handling, and special labor charges are not refundable.  We reserve the right to refuse service to any customer, for any reason, at any time.  All custom programming done by us is copyrighted.  Sharing of our custom programming with anyone besides the original customer without our written consent, is prohibited by law and will void the support agreement.  We shall not be held responsible for any misuse, operation, nor any other intentional or unintentional use of any custom program in and including any vehicle, on or off road; nor shall we be held responsible for any accidents, injuries, fatalities, or property damages where our custom programming is used or was once used.  In other words, by using our custom programming, you acknowledge that you take full responsibility for any and all situations that may occur while using the custom program, and thus we will NOT be held accountable for anything, whatsoever.  If you have any other questions, please feel free to email us.

If you require our custom tuning service, and agree with the terms and conditions listed above, please take a moment and fill out this quick online form: CLICK HERE (you may be asked to fill out a more-comprehensive form later)


If you do not require our services, or you do not agree with our terms and conditions; you may return to the Sinister Performance home page by clicking on the link below.

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You may have noticed that we do not have a phone number or address listed on this website.  The reasons for this can be read by clicking here.  However, we are happy to supply you with an email address that gets checked about once every business day, except on holidays.  We supply our shipping address to all custom chip/programming customers.  However, the easiest and best way to contact us is via EMAIL.