That's pretty decent. After spending the last year replacing misc. sensors and exhaust parts my Sport with a SAS and 35s is back up to 18-19 on the highway. A little tweeking and there's no reason you shouldn't be able to keep that real close to 19 even with larger tires.

Edward

'97 Montero Sport LS 5-Speed 3.5L conversion
SAS Dana 44s & ARBs, 35" Yoko Geolandar M/Ts
NP231 B4R doubler/Terra Low231/RP 5.38 229:1
'99 Montero Sport Limited 4WD SAS 3-link project
'03 Montero Sport Limited AWD
'97 Montero Sport LS 5-Speed 4WD