Well they do not pay for add ons like my front splitter but are you reffering to the DINAN exhaust as I think they will if its comparable in price to the OEM. They have for me in the past.
For this situation, yes they should. An individual's insurance company will likely not replace an expensive aftermarket part if you damage your own car, but if someone else damages your car then I would demand they return it to the same condition it was in before the accident.
This happened to me (somewhat). I got rear-ended and the other driver's insurance company tried to tell me they use non-OEM replacement parts. On top of that, they tried to tell me to use their cut-rate body shop. I told them NFW on both - I told them their customer hit me through no fault of my own, so I'm going to the body shop of my choice and the car is being repaired with new (no reconditioned) OEM parts. They still tried to bully me and I just said they had 2 choices (1) they could accept my proposal, or (2) I would repair the car through my insurance company and have my company contact them for reimbursement of the repair plus a significant diminished value claim. As soon as I said "deminished value claim" they suddenly became a lot more agreeable to my original proposal.
2007 e60 m5 6MT Interlagos Blue; RPI Oil Cooler and Scoops; DINAN High Flow Air Mass Meter and Intake, DINAN 3.91 diff, DINAN strut, DINAN software, DINAN High Flow Middle Racing Exhaust (secondary cat delete) with 3.5" Resonators, DINAN Free Flow Section 3 Exhaust, DINAN 19x9 ET18, 19x10 ET25, Michelin PSS 255/40/19 and 305/30/19, Macht Schnell 15mm spacers (front); Motul RBF 660; Hawk HT-10s pads; RDSport/StopTech BBK 380mm/35mm x 380mm/32mm, RD Sport Front and Rear sways; CKS coils w/swift springs; z3 1.9L SSK, with f10 shifter; Escort RedLine hardwired and Bel STiR+ coming. 81,000 miles with no RCOD and counting...
2000 e39 m5 TiAg; PSS9 Coilover; AA Intake/Tune and sink drains; Custom Britalman exhaust (just now retired from my daily driver duties and on loan with my retired Pops!)
1988 e28 m5 STROKER (Paul Burke s38b38); The one that started it all; the one I'll never sell...Euro Headers, custom Ground Control Coilovers undergoing full Euro restoration.
1996 FZJ 80; TRD Supercharger; Expo/Overland/Backcountry Rig; custom sleeper/drawer system, full rock armor, 33"s on 2.5" OME Heavy Lift.
2008 Audi A3 S-Line Quattro (Mammoth Mountain Commuter)
Dang, wasn't my beast but I'm screaming right along with you. Glad all parties are ok! Please make sure the insurance company does not try to cut corners. In addition to the other apparent issues, the exhaust system will need to be checked from the headers as well to make sure they are properly secured to the heads. Frame, rear suspension components, drive shaft, floor pan etc. You know the drill, be meticulous. Hope it all shakes out well for you!!!!
Their insurance has to cover repairs to the vehicle, and that includes the aftermarket exhaust. I would make sure your insurance company fights for that. Otherwise you may need to sue the other driver for the additional damages.
Sorry to see that, but definitely repairable. Other driver's car got it way worse than yours.