diff --git a/bom.txt b/bom.txt
index e72e22d..7e7c259 100644
--- a/bom.txt
+++ b/bom.txt
@@ -1,8 +1,8 @@
-BOM for Afterburner PCB 3.1
+BOM for Afterburner PCB 3.2b
 ============================
-* (R1 - 4x) Resistor 4k7 (TH or SMT 0805) 0.25W, 5% or better tolerance  - 4x
+* (R1 - 5x) Resistor 4k7 (TH or SMT 0805) 0.25W, 5% or better tolerance  - 5x
 * (R8, R4) Resistor 10k (TH or SMT 0805) 1% or better tolerance - 2x
-* (R5) Resistor 100k (TH or SMT 0805) 1% or better tolerance - 1x
+* (R5, R18) Resistor 100k (TH or SMT 0805) 1% or better tolerance - 2x
 * (R6) Resistor 20k (TH or SMT 0805) 1% or better tolerance - 1x
 * (R7, R3, R2) Resistor 3k3 (TH or SMT 0805) 1% or better tolerance - 3x
 * (R9) Cermet trimmer (TH Suntan TSR-3362P-202R 2k) - 1x
@@ -26,3 +26,29 @@ BOM for Afterburner PCB 3.1
 * 40 Pin Male Single Row Strip 2.54mm Pin Header Connector 0.1" Straight - 1x
 * Arduino UNO
 
+
+OPTIONAL features
+-----------------
+on-board voltage booster (replacement for MT3608 module)
+
+* (R10, R13 ,R14) Resistor 100k (TH or SMT 0805) 1% or better tolerance - 3x
+* (R11) Resistor 4k7 (TH or SMT 0805) 0.25W, 1% or better tolerance  - 1x
+* (R12) Resistor 3k3 (TH or SMT 0805) 1% or better tolerance - 1x
+* (C10) Capacitor ceramic 1uF, 9V or higher (TH or SMT 0805) - 1x
+* (D2)  Diode Schottky SK14, 1A 40V (SMT package DO-214AC-2 )
+        or alternative TH Schottky diode 1N5818
+* (L1)  Inductor 10uH, NLCV32T-100K-PF  (SMT package 1210)
+        or alternative TH: AICC-02-100K-T Axial inductor
+* (U3)  Voltage booster MIC2619 (SOT-23-6) with over voltage protection (OVP)
+        or alternative MIC2250  (SOT-23-5) without OVP, R10, R11 and R12 not required
+        or possibly TPS61040DBVR (SOT-23-5) without OVP - not tested yet
+
+SPI-RAM: extra memory for UNO (not used ATM. Can be soldered later if needed)
+
+* (R15, R16)  Resistor 10k (TH or SMT 0805) 5% or better tolerance - 2x
+* (R17) Resistor 4k7 (TH or SMT 0805) 0.25W, 5% or better tolerance  - 1x
+* (C11) Capacitor ceramic 100nF 10V or higher (TH or SMT 0805) - 1x
+* (Q2,Q3) N-MOSFET (SMT: BSS138P - SOT23 or TH: BS170G - TO92, or similar)  - 2x
+* (U4)  SPI-RAM 5V, 23LC1024, DIP or SOIC-8, alternative 23LC512 or 23LCV512 or 23LCV1024
+
+