They have Lingenfelter Vipers!
Viper 510 CID 1992 - 2001
RT/10, GT2, GT2 & ACR
Street ET Slicks
0-60- 2.9 seconds
1/4 mile- 10.5@133mph
As tested by Car & Driver:
http://www.lingenfelter.com/pac510cidvip.asp
http://www.lingenfelter.com/pac540cidvip.asp