The duo are two of five new faces to the forward pack, with a further three personnel changes made to the backline for the crucial Guinness PRO12 encounter.
Herbst is part of a front row that also includes captain Rob Herring and loosehead prop Callum Black.
Tuohy will join Franco van der Merwe in the second row, while Robbie Diack also returns to the starting team; he is picked alongside Sean Reidy and Roger Wilson in the back row.
Ruan Pienaar and Paddy Jackson are retained in the half-back positions, with Darren Cave joining Luke Marshall in midfield. Tommy Bowe and Craig Gilroy have been elevated from the bench to starting berths on the wing, so last week's Man of the Match Charles Piutau switches to fullback.
Conor Joyce could make his first appearance for the Province in over two years after being named among the replacements. The 23-year-old back row's last outing was the memorable 17-19 win over Munster at Thomond Park in May 2014.
John Andrew, Kyle McCall, Andy Warwick and Clive Ross will provide additional cover for the forwards, with Paul Marshall, Brett Herron and Jacob Stockdale included in the match day squad as backline options.
Unfortunately, after sustaining a hip flexor injury, Stuart Olding is likely to be out of action for at least two matches. As expected, Iain Henderson will also miss this weekend's action. Iain has shown improvement this week following a shoulder injury picked up against Exeter and he will be continue to be assessed on a weekly basis.
Ulster team and replacements to play Munster, Friday 28th October, Kingspan Stadium (kick-off 7.05pm):
(15-9): C Piutau; T Bowe, L Marshall, D Cave, C Gilroy, P Jackson, R Pienaar;
(1-8): C Black, R Herring (capt), W Herbst, D Tuohy, F van der Merwe, R Diack, S Reidy, R Wilson;
Replacements (16-23): J Andrew, K McCall, A Warwick, C Ross, C Joyce, P Marshall, B Herron, J Stockdale.
Match Stats:
- Ulster Rugby were defeated by Connacht in Galway in round 6, their first loss of this campaign, and have not lost successive Guinness PRO12 encounters since February.
- Ulster have won their last seven matches in Belfast in all tournaments since Scarlets were successful there by a single point in the PRO12 on 21st February.
- Munster Rugby tripped up at Leinster in round 6 of the Guinness PRO12 but have not lost back-to-back fixtures in the Championship since April.
- Munster's only success against a fellow Irish province in their last six such encounters was the 9-7 win in this equivalent fixture last season.
- Munster are unbeaten in their last four meetings with Ulster since the Ulstermen triumphed 19-17 at Thomond Park in the PRO12 in May 2014.
- Munster are unbeaten on their last two visits to Kingspan Stadium and have not gone three matches without defeat in Belfast since the Second World War.
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