I've done the 1st to 6th shift before
But seriously though, it's stupid to go that slow in 6th gear - it's an overdrive gear for higher speeds. You're getting worse gas trying to accelerate from 35 mph in 6th gear than if you were in 3rd or 4th gear.
I'll also point out that my Fast Intentions exhaust is deeper and louder when you bog the car with throttle at low RPMs. I've found the perfect RPMs for stealth is right around 3000 in the appropriate gear for your speed with just enough throttle to maintain speed on level ground. Plus much closer to the power band than 1500 RPMs