(adsbygoogle = window.adsbygoogle || []).push({}); This is a guide on how you can extend the usable rev-range of a car beyond it's natural capabilities. Now this is mostly for creating a more unique sound, power results can vary and sometimes give lower power levels than expected. There are ways to overcome this, and I've detailed a few examples later in this guide.
As with all editing, keep a backup of your save for reverting any mistakes you make.

Things you will need:

1. A USB storage device (Should be found in or around the area of your PS3 or PC)
   
2. A computer (Look on a table or desk, possibly under a pile of paperwork or books)
   
3. A copy of Slim's Garage editor You must login or register to view this content.
   
4. A copy of Bruteforce & HXD (Look for it on your computer, or the internet)
   
5. A clue about what you are doing with all of the above (Only you know where this one is)
   

Stage One - Initial setup.

Choose your project car and get into it. Buy all the components you are likely to be replacing during the hex process, including the stage 3 turbo, if this option is available. Any component you change within hex needs to be already installed on the car if you want to be able to adjust them in-game after the editing process. Do not perform the engine stage upgrades, you'll need them later on.

Copy your save to the USB device and then onto your computer, as you would normally do. Also, make a second copy in a memorable location, but NOT the desktop. This second location will be used as a reference save file only, and can also be used if you really mess things up.

Make sure you are in your "project" car, then locate your car as you would normally within HXD and find your turbo code. This will be exactly two rows below the code for your suspension. (If you don't know where this is, then perhaps this guide is not for you, just leave it alone now and don't message me for an explanation, You must login or register to view this content.)

Stage Two - Stretching.

CAUTION - You need to make sure the engine you are transplanting in has a default turbo code of 091D
For this step you need to open Garage Editor using the second save location you created, go to the Garage and check the stock version of the car. The next part will only work, whilst retaining an exhaust note, if the default code matches the ones I mentioned.

Replace the entire eight digits of the turbo with FF FF xx xx (xx being the turbo code of a stage 3 turbo, for example FF FF 15 26 is the Scwimmwagen's stage 3 turbo with the stretch code)
Once you have finished replacing all the components, copy back to your USB and into the game.

Stage Three - Stabilisation.

Once loaded back into the game, do your oil change. Now, this will show you a ridiculous amount of horsepower, sometimes upwards of five-figures. IGNORE IT! as you're about to ditch that completely useless power and make it a more useful output.
Go and buy the engine tune stages, you will notice the power has dramatically decreased, back to levels that would be considered "normal". Add all the power parts except for turbos or superchargers. Adding these will completely reverse the stretching process.
Head back to your garage and go into the settings of the car, you will find the rev range has been changed, with peak power being raised by quite a way. In order to see the absolute maximum revs the engine will now give, go into your transmission setup. The redline/engine cutout revs are marked at the top of the gear graph.

Stage Four - Options and other thoughts.

I tend to find that sometimes the power levels may be too low for the project car I'm creating. I will experiment with different turbo codes and even add in a supercharger to boost the lower end of the rev range when using a turbo that only works at the top end of the scale. Adding the Racing Catalytic converter will also raise the power a little too. You may also want to add in a boost controller, though for the most part this is just for appearance than functionality.

In most cases, you'll find that the power, torque or both will be lower when you approach the end of the rev scale. This is completely normal, you will always find more power below the end of the stretch. The stretch itself is more for the uniqueness of the sound it creates than as a power booster.

If your exhaust note disappears you need to check one of the following:

• If you have used a race car engine, make sure you have the racing exhaust fitted, as 99.9% of the race cars have this as their only installable exhaust. Removing this removes the sound.
  
• Check the "donor" engine you have installed into the "project" car has the correct default turbo code. If it has something different the sound will disappear, as the engine is designed to be used with an installed turbo. Despite the stretch code containing a turbo code, the game sees it as being removed due to the FF's before it.
  

Final thoughts.
Any questions along the lines of "where do I find,,,?" or "what is the hex code for,,,?" will be completely ignored. If you don't already know, you probably don't have the competence required to perform this, or any other, hex mod without potentially ruining your save file, FOR WHICH I WILL NOT BE HELD ACCOUNTABLE. If you can't be bothered to do the research, don't expect to get spoon-fed the results. There is more than enough information on this website in order to get to the level where doing this sort of thing becomes second nature, not to mention the vast array of tools available to make things simpler if you're not comfortable with HEX editing.

IF YOU'RE NOT 100% SURE OF WHAT YOU'RE DOING, DON'T DO IT!

Project Example - Renault Avantime - Acceleration test.

Renault Avantime
Honda Weider HSV engine
1108bhp at 10,400rpm (Rev max - 15,200rpm)
Scwimmwagen stage 3 turbo, Shelby Series One supercharger

then i must be doing something wrong then... lol when i do the oil change, i get the outrageous power, but when i add all the power adders, i check the rev range and its not stretched...