Dans car got about 35hp gains and your not going to see his car pull away just from extra 35hp, especially on our cars that weigh a lot to begin with. However you will start seeing the difference on the big open highways. Not only that, throttle response is also improved.
My friend had his tuned by this tuner that I cannot mention name, he tuned the Mclaren F1 cars, Nissan GTR 24 hr lemans cars, many exotics etc etc. Gained abt 43hp, 34nm of torque on dyno. Throttle opened to 100%, stock is only 75% due to Euro standards. He asked him before the tune how much power will he get and he replied to him "you try and tell me". Thats how confident he was. He has been tuning 28 years already. However you will not find him over the net, keeps very low key because he's tied up with these big companies.
His car now feels so much quicker off the line and pulls hard to redline. A tune is a must for Masers because as we all know the factory gives it a very conservative tune to keep numbers way below Ferrari. Now he feels his tune is up to spec and he loves it to death.
So yes a tune is a must for Masers but don't expect day and night difference over 30-40hp but overall you will feel a good difference which you will see on the big open highways. I also say you will feel the difference on the big open highways because he did manage to pull a couple of car lengths ahead of his friends stock Maser for some drive they recently did. DMS in my opinion is very good, excellent credibility. Good luck guys.