The downpipes are made of T-304 stainless steel 
Will fit the following models:
 
BMW M3 F80
BMW M4 F82
 
Features:
Stainless Steel construction 
Tig Welded with Cast ends on turbo side.
3” diameter 
Fit to stock exhaust or any after market exhaust that fits the stock downpipes
Allows quicker turbo spool for higher response
60-70 BHP & 70-80 lb/ft torque when combined with Stage 2 Tuning 
Provides a deeper and sportier exhaust note.