I'm pretty sure that if your Vspec has 5 gallons though it, it probably needs a rebuild and pinch. It may be time for a new crank as well. I ran a Vspec this past summer in my MBX6T for two months. I used a Dynamite 007ht and 1.0 springs. It had tremendous bottom end and decent mid to top end power.

My vspec lost compression after 2 1/2 gallons. I had it rebuilt and pinched and it was good as new. My engine guy did say that I'd need a new crank after another gallon or so. If I were you I would have it looked over by someone who can pinch and rebuild it for you.