Not your OEM belt.

[CHEVY-212010]

kind of an update on the spree. Getting new jets in a day and tuning begins, but performance by chance today. took the spree to the gym and it rained. the craftsman filter got wet and it would not run. decided to pull the filter off and performance gain! The throttle response is weird but if i had a decent strait away i bet she would push upper thirtys 37-39. i know that the speedo is wrong so what about would that be?
anyway

Mike

[Lunytune]

i know that the speedo is wrong so what about would that be?

You need a GPS to know for sure. Great little gadgets.

[Wheelman-111]

Greetings:

It's easy to anticipate Speedometer Error. Knock off about 10% and you'll be very close, hence 39 indicated + ~35 true.
Switching to a bigger front tire will offset much of the error. A 3.00 mounted tire has about a 7% bigger diameter than a 2.5", presuming it fits. If not a 2.75 will reduce your speedo's optimism by almost half. Both will improve the ride considerably.