I had tunes from both, I would go with pcm for less. Ion did a terrible job for me. I have the 306 cam. p&p heads. bigger injectors/t.b. and other mods. he sent me a tune. and it was running really lean, tried to get him to take it back to adj. it, he would not do it, kept saying his tune was dead on. went on a dyno with a/f. and it was dangerously lean. he still wouldn't take it back, wanted me to buy the moates setup. and adj. it myself. after many emails bickering back and fourth on him saying his tune was right and my car was screwed up. I finally found a person here in KC that tuned my car, and guess what? the problem was his tune. finally gotten it straightened out. and emailed Ion and told him it was his tune, never returned my email. so I told him I will let everyone know about my experience about him. every time I do I get around 5 pm's. from people who he has also done it to. Ion is a Jerk, and self centered. once he get's his money he is done with you. this is my experience with him. Im sure he has done other people right, but not me. I wasted $125.00 on him... Alvin did me right with his tune.I haven't ever had a problem with Alvin from pcmforless. So personally I would go with pcmforless...