A porous ceramic honeycomb body, comprising: a primary cordierite ceramic phase having: a median pore size diameter d 50 less than 7.9 microns; a thermal shock parameter of at least 450°C; an elastic modulus ratio E ratio of not more than 1.01, wherein TSP is (MOR 25°C /E 25°C)(CTE 500-900°C) -1, MOR 25°C is the modulus of rupture strength at 25°C, E 25°C is the Young's elastic modulus at 25°C, and CTE 500-900°C is the high temperature thermal expansion coefficient at 500°C to 900°C, and E ratio = E 900°C /E 25°C where E 900°C is the elastic modulus at 900°C measured during heating; excluding cordierite honeycomb bodies A and B having the following properties: A B %Y 2 O 3 1.0 1.0 % Porosity 62.6 60.1 d 1 1.7 1.5 d 2 2.2 1.7 d 5 2.9 2 d 10 3.4 2.3 d 25 4.2 2.7 d 50 5.2 3.1 d 75 6.5 3.5 d 90 11.6 4.7 d 95 44 8.6 d 98 155.2 18.8 d 99 210.6 38.4 (d 50 -d 10)/ d 50 = d f 0.35 0.26 (d 90- d 10)/ d 50 = d b 1.58 0.77 PCF = %Porosity/d b 40 78 CTE, 25-800 (10 -7 /°C 13.2 12 CTE, 500-900 (10 -7 /°C 19.4 19.2 CTE, 200-1000 (10 -7 /°C) 17.1 16.7 Δα mc 25-800 (10 -7 /°C 0.6 1.3 Axial I-Ratio 0.48 0.46 Transverse I-Ratio (I T) 0.82 0.83 ΔI = I T -I A 0.34 0.37 % Mullite 0 0 % Spinel + Sapphirine 1.6 1.7 % Alumina 0 0 Cell Density (Cells/mm 2) 0.93 [600 cells/inch 2] 0.93 [600 cells/inch 2] Wall thickness (10 -3 mm) 101.6 [4 x 10 -3 inches] 101.6 [4 x 10 -3 inches] Closed Frontal Area 0.186 0.186 MOR 25°C (kPa) 2048 [297 psi] 2820 [409 psi] MOR/CFA (kPa) 11011 [1597 psi] 15162 [2199 psi] E 25°C (10 5 kPa) 12.48 [1.81 x 10 5 psi] 19.24 [2.79 x 10 5 psi] E 900°C (10 5 kPa) 11.58 [1.68 x 10 5 psi] 18.20 [2.64 x 10 5 psi] E 1000°C (10 5 kPa) 10.62 [1.54 x 10 5 psi] 16.69 [2.42 x 10 5 psi] E 900°C / E 25°C 0.93 0.95 E 1000°C / E 25°C 0.85 0.87 Microcrack Parameter (Nb 3) 0.014 0.017 MOR/ E 25°C 0.164% 0.147% TSP = MOR/[E*CTE] 846 764 TSL = TSP + 500 1346 1246 TSP* = MOR/[E*CTE] 960 878 TSL* = TSP* + 200 1160 1078 wherein: d n denotes the pore diameters at which n% of the pore volume of the material resides in pores of smaller pore diameter; Nb 3 consists of N, which is the number of microcracks per unit volume of ceramic, and b, which is the diameter of the microcracks; and Δα mc 25-800 is the thermal expansion differential factor across 25°C to 800°C. a primary cordierite ceramic phase having: a median pore size diameter d 50 less than 7.9 microns; a thermal shock parameter of at least 450°C; an elastic modulus ratio E ratio of not more than 1.01, a median pore size diameter d 50 less than 7.9 microns; a thermal shock parameter of at least 450°C; an elastic modulus ratio E ratio of not more than 1.01, wherein TSP is (MOR 25°C /E 25°C)(CTE 500-900°C) -1, MOR 25°C is the modulus of rupture strength at 25°C, E 25°C is the Young's elastic modulus at 25°C, and CTE 500-900°C is the high temperature thermal expansion coefficient at 500°C to 900°C, and E ratio = E 900°C /E 25°C where E 900°C is the elastic modulus at 900°C measured during heating; excluding cordierite honeycomb bodies A and B having the following properties: A B %Y 2 O 3 1.0 1.0 % Porosity 62.6 60.1 d 1 1.7 1.5 d 2 2.2 1.7 d 5 2.9 2 d 10 3.4 2.3 d 25 4.2 2.7 d 50 5.2 3.1 d 75 6.5 3.5 d 90 11.6 4.7 d 95 44 8.6 d 98 155.2 18.8 d 99 210.6 38.4 (d 50 -d 10)/ d 50 = d f 0.35 0.26 (d 90- d 10)/ d 50 = d b 1.58 0.77 PCF = %Porosity/d b 40 78 CTE, 25-800 (10 -7 /°C 13.2 12 CTE, 500-900 (10 -7 /°C 19.4 19.2 CTE, 200-1000 (10 -7 /°C) 17.1 16.7 Δα mc 25-800 (10 -7 /°C 0.6 1.3 Axial I-Ratio 0.48 0.46 Transverse I-Ratio (I T) 0.82 0.83 ΔI = I T -I A 0.34 0.37 % Mullite 0 0 % Spinel + Sapphirine 1.6 1.7 % Alumina 0 0 Cell Density (Cells/mm 2) 0.93 [600 cells/inch 2] 0.93 [600 cells/inch 2] Wall thickness (10 -3 mm) 101.6 [4 x 10 -3 inches] 101.6 [4 x 10 -3 inches] Closed Frontal Area 0.186 0.186 MOR 25°C (kPa) 2048 [297 psi] 2820 [409 psi] MOR/CFA (kPa) 11011 [1597 psi] 15162 [2199 psi] E 25°C (10 5 kPa) 12.48 [1.81 x 10 5 psi] 19.24 [2.79 x 10 5 psi] E 900°C (10 5 kPa) 11.58 [1.68 x 10 5 psi] 18.20 [2.64 x 10 5 psi] E 1000°C (10 5 kPa) 10.62 [1.54 x 10 5 psi] 16.69 [2.42 x 10 5 psi] E 900°C / E 25°C 0.93 0.95 E 1000°C / E 25°C 0.85 0.87 Microcrack Parameter (Nb 3) 0.014 0.017 MOR/ E 25°C 0.164% 0.147% TSP = MOR/[E*CTE] 846 764 TSL = TSP + 500 1346 1246 TSP* = MOR/[E*CTE] 960 878 TSL* = TSP* + 200 1160 1078 wherein: d n denotes the pore diameters at which n% of the pore volume of the material resides in pores of smaller pore diameter; Nb 3 consists of N, which is the number of microcracks per unit volume of ceramic, and b, which is the diameter of the microcracks; and Δα mc 25-800 is the thermal expansion differential factor across 25°C to 800°C. d n denotes the pore diameters at which n% of the pore volume of the material resides in pores of smaller pore diameter; Nb 3 consists of N, which is the number of microcracks per unit volume of ceramic, and b, which is the diameter of the microcracks; and Δα mc 25-800 is the thermal expansion differential factor across 25°C to 800°C.