The answer to this question depends on what exemption code was used (section 703 or 704).
Also, do you have other assets and did you apply exemptions to those?
If you have the exemptions available, you can amend the petition (subject to Trustee approval).
If there is a problem, you will likely have to hire an attorney to file a motion before the court for determination of asset value.
Yes, you can use the maximum exemption allowed to protect your property by amending Schedule C as necessary. However, be careful not to undervalue the property because you might be denied the exemption. Be ready to justify the value of each piece of property you list on Schedules A and B.