The main explosion particles bounce off the floor too

src/dehacked.c

@@ -7017,6 +7017,7 @@ static const char *const MOBJTYPE_LIST[] = {  // array length left dynamic for s
 	"MT_BOMBEXPLOSIONSOUND",
 
 	"MT_SMOLDERING", // New explosion
+	"MT_BOOMEXPLODE",
 	"MT_BOOMPARTICLE",
 
 	"MT_BLUELIGHTNING", // Lightning stuff

src/info.c

@@ -15056,6 +15056,33 @@ mobjinfo_t mobjinfo[NUMMOBJTYPES] =
 		S_NULL          // raisestate
 	},
 
+	{           // MT_BOOMEXPLODE
+		-1,             // doomednum
+		S_SLOWBOOM1,    // spawnstate
+		1,              // spawnhealth
+		S_NULL,         // seestate
+		sfx_None,       // seesound
+		0,              // reactiontime
+		sfx_None,       // attacksound
+		S_NULL,         // painstate
+		0,              // painchance
+		sfx_None,       // painsound
+		S_NULL,         // meleestate
+		S_NULL,         // missilestate
+		S_NULL,         // deathstate
+		S_NULL,         // xdeathstate
+		sfx_None,       // deathsound
+		1,              // speed
+		16*FRACUNIT,    // radius
+		32*FRACUNIT,    // height
+		0,              // display offset
+		0,              // mass
+		0,              // damage
+		sfx_None,       // activesound
+		MF_NOBLOCKMAP|MF_NOGRAVITY|MF_BOUNCE|MF_SCENERY, // flags
+		S_NULL          // raisestate
+	},
+
 	{           // MT_BOOMPARTICLE
 		-1,             // doomednum
 		S_INVISIBLE,    // spawnstate

src/info.h

@@ -3999,6 +3999,7 @@ typedef enum mobj_type
 	MT_BOMBEXPLOSIONSOUND,
 
 	MT_SMOLDERING, // New explosion
+	MT_BOOMEXPLODE,
 	MT_BOOMPARTICLE,
 
 	MT_BLUELIGHTNING, // Lightning stuff

src/k_kart.c

@@ -2196,10 +2196,9 @@ void K_SpawnBobombExplosion(mobj_t *source, UINT8 color)
 
 		truc = P_SpawnMobj(source->x + P_RandomRange(-radius, radius)*FRACUNIT,
 			source->y + P_RandomRange(-radius, radius)*FRACUNIT,
-			source->z + P_RandomRange(0, height)*FRACUNIT, MT_BOSSEXPLODE);
+			source->z + P_RandomRange(0, height)*FRACUNIT, MT_BOOMEXPLODE);
 		truc->scale = source->scale*2;
 		truc->destscale = source->scale*6;
-		P_SetMobjState(truc, S_SLOWBOOM1);
 		speed = FixedMul(10*FRACUNIT, source->scale)>>FRACBITS;
 		truc->momx = P_RandomRange(-speed, speed)*FRACUNIT;
 		truc->momy = P_RandomRange(-speed, speed)*FRACUNIT;

src/p_mobj.c

@@ -3038,11 +3038,22 @@ static boolean P_SceneryZMovement(mobj_t *mo)
 
 	switch (mo->type)
 	{
+		case MT_BOOMEXPLODE:
 		case MT_BOOMPARTICLE:
 			if ((mo->flags & MF_BOUNCE) && (mo->z <= mo->floorz || mo->z+mo->height >= mo->ceilingz))
 			{
+				// set standingslope
+				P_TryMove(mo, mo->x, mo->y, true);
 				mo->momz = -mo->momz;
-				mo->z += mo->momz;
+#ifdef ESLOPE
+				if (mo->standingslope)
+				{
+					if (mo->flags & MF_NOCLIPHEIGHT)
+						mo->standingslope = NULL;
+					else if (!P_IsObjectOnGround(mo))
+						P_SlopeLaunch(mo);
+				}
+#endif
 				S_StartSound(mo, mo->info->activesound);
 			}
 			break;