modifications for better towing

If you have a GM Duramax or a Dodge Cummins, you can take advantage of custom tuning by diesel shops that tune with EFI Live. They can custom "tune" the ECU in your truck to optimize power in a safe manner. You can also have turbo braking on diesels that have VVT. If done properly by a knowledgeable tech, you can improve fuel economy, power and driveability without sacrificing engine longevity and you can have several modes available for towing, enhanced stock tune, valet (governed power) or whatever you would like, including high performance-not recommended for towing. The key is in finding someone who knows what they are doing.