I'm almost positive NGK has stopped making plugs with removable tips. Can't find any anywhere. Sifted through boxes and boxes of plugs behind the counter at a store and found nada.
Bosch consistently offers removable tips still, so I went hunting for a part number that will work for me. I found the number comparable in heat range to the NGK-7 which is "6". Factory heat range for Bosch plug for our N/A engines is 8. Two steps colder (lower numbers are colder for American companies and higher for Japanese companies usually) from 8 is 6. By the way, here's
the site I used to mostly decode the various brand's part numbers. It also has tons of fun info so it's a good read (Mitsubishi 3000GT centric but tons of good general info).
FR8DCX+ is factory. FR6DCX+ is what I need (in copper).
I also used
www.sparkplugs.com to find other cars that run this colder plug from the factory so I can just show up at a local place and say "I have a 1998 Toyota Supra Twin Turbo I need plugs for" and avoid dealing with the madness.
List of factory cars with plug sizes and heat ranges comparable to what I'm looking for (cool cars to pretend you own marked in bold):
ACURA INTEGRA GSR (2001) 1.8LL4 B18C1
ACURA INTEGRA GSR (2000) 1.8LL4 B18C1
ACURA INTEGRA GSR (1999) 1.8LL4 B18C1
ACURA INTEGRA GSR (1998) 1.8LL4 B18C1
ACURA INTEGRA GSR (1997) 1.8LL4 B18C1
ACURA INTEGRA GSR (1996) 1.8LL4 B18C1
ACURA INTEGRA GSR (1995) 1.8LL4 B18C1
ACURA INTEGRA GSR (1994) 1.8LL4 B18C1
ACURA INTEGRA TYPE-R (2001) 1.8LL4 B18C5
ACURA INTEGRA TYPE-R (2000) 1.8LL4 B18C5
ACURA INTEGRA TYPE-R (1998) 1.8LL4 B18C5
ACURA INTEGRA TYPE-R (1997) 1.8LL4 B18C5
HONDA CIVIC MUGEN SI (2008) 2.0LL4 K20Z3
HONDA CIVIC SI (2008) 2.0LL4 K20Z3
HONDA CIVIC SI (2007) 2.0LL4 K20Z3
HONDA CIVIC SI (2006) 2.0LL4 K20Z3
HONDA S2000 (2008) 2.2LL4 F22C1
HONDA S2000 (2007) 2.2LL4 F22C1
HONDA S2000 (2006) 2.2LL4 F22C1
HONDA S2000 (2005) 2.2LL4 F22C1
HONDA S2000 (2004) 2.2LL4 F22C1
HONDA S2000 CR (2008) 2.2LL4 F22C1
INFINITI M30 (1991) 3.0LV6 VG30E
INFINITI M30 (1990) 3.0LV6 VG30E
NISSAN 200SX (1988) 3.0LV6 VG30E
NISSAN 200SX (1987) 3.0LV6 VG30E
NISSAN 300ZX (1996) 3.0LV6 VG30DE
NISSAN 300ZX (1996) 3.0LV6 VG30DETT
NISSAN 300ZX (1995) 3.0LV6 VG30DE
NISSAN 300ZX (1995) 3.0LV6 VG30DETT
NISSAN 300ZX (1994) 3.0LV6 VG30DE
NISSAN 300ZX (1994) 3.0LV6 VG30DETT
NISSAN 300ZX (1993) 3.0LV6 VG30DE
NISSAN 300ZX (1993) 3.0LV6 VG30DETT
NISSAN 300ZX (1992) 3.0LV6 VG30DE
NISSAN 300ZX (1992) 3.0LV6 VG30DETT
NISSAN 300ZX (1991) 3.0LV6 VG30DE
NISSAN 300ZX (1991) 3.0LV6 VG30DETT
NISSAN 300ZX (1990) 3.0LV6 VG30DE
NISSAN 300ZX (1990) 3.0LV6 VG30DETT
NISSAN 300ZX (1989) 3.0LV6 VG30
NISSAN 300ZX (1988) 3.0LV6 VG30
NISSAN 300ZX (1987) 3.0LV6 VG30
NISSAN 300ZX (1986) 3.0LV6 VG30
NISSAN 300ZX (1986) 3.0LV6 VG30T
NISSAN 300ZX (1985) 3.0LV6 VG30
NISSAN 300ZX (1984) 3.0LV6 VG30
NISSAN 300ZX 2+2 (1996) 3.0LV6 VG30DE
NISSAN 300ZX 2+2 (1995) 3.0LV6 VG30DE
NISSAN 300ZX 2+2 (1994) 3.0LV6 VG30DE
NISSAN 300ZX 2+2 (1993) 3.0LV6 VG30DE
NISSAN 300ZX 2+2 (1992) 3.0LV6 VG30DE
NISSAN 300ZX 2+2 (1991) 3.0LV6 VG30DE
NISSAN 300ZX 2+2 (1990) 3.0LV6 VG30DE
NISSAN 300ZX 2+2 (1989) 3.0LV6 VG30
NISSAN 300ZX 2+2 (1988) 3.0LV6 VG30
NISSAN 300ZX 2+2 (1987) 3.0LV6 VG30
NISSAN 300ZX 2+2 (1986) 3.0LV6 VG30
NISSAN 300ZX 2+2 (1986) 3.0LV6 VG30T
NISSAN 300ZX 2+2 (1985) 3.0LV6 VG30
NISSAN 300ZX 2+2 (1984) 3.0LV6 VG30
NISSAN MAXIMA (1991) 3.0LV6 VG30E
NISSAN MAXIMA (1990) 3.0LV6 VG30E
NISSAN MAXIMA (1989) 3.0LV6 VG30E
NISSAN MAXIMA (1988) 3.0LV6 VG30E
NISSAN MAXIMA (1987) 3.0LV6 VG30E
NISSAN MAXIMA (1986) 3.0LV6 VG30E
NISSAN MAXIMA (1985) 3.0LV6 VG30E
NISSAN MAXIMA GXE (1994) 3.0LV6 VG30E
NISSAN MAXIMA GXE (1993) 3.0LV6 VG30E
NISSAN MAXIMA GXE (1992) 3.0LV6 VG30E
SAAB 3-Sep (2001) 2.0LL4 B205L
SAAB 3-Sep (2000) 2.0LL4 B205L
SAAB 3-Sep (1999) 2.0LL4 B204L
SAAB 3-Sep SE (2003) 2.0LL4 B205R
SAAB 3-Sep SE (2002) 2.0LL4 B205R
SAAB 3-Sep SE (2001) 2.0LL4 B205R
SAAB 3-Sep SE (2000) 2.0LL4 B205R
SAAB 3-Sep VIGGEN (2002) 2.3LL4 B235R
SAAB 3-Sep VIGGEN (2001) 2.3LL4 B235R
SAAB 3-Sep VIGGEN (2000) 2.3LL4 B235R
SAAB 3-Sep VIGGEN (1999) 2.3LL4 B235R
SAAB 5-Sep ARC (2005) 2.3LL4 B235L
SAAB 5-Sep ARC (2004) 2.3LL4 B235L
SAAB 900 S TURBO (1998) 2.0LL4 B204L
SAAB 900 SE TURBO (1998) 2.0LL4 B204L
SAAB 900 SE TURBO (1997) 2.0LL4 B204L
SAAB 9000 (1992) 2.3LL4 B234L
SAAB 9000 (1991) 2.3LL4 B234L
SAAB 9000 AERO (1996) 2.3LL4 B234L
SAAB 9000 AERO (1996) 2.3LL4 B234R
SAAB 9000 AERO (1995) 2.3LL4 B234L
SAAB 9000 AERO (1995) 2.3LL4 B234R
SAAB 9000 AERO (1993) 2.3LL4 B234L
SAAB 9000 CD (1994) 2.3LL4 B234L
SAAB 9000 CD (1993) 2.3LL4 B234L
SAAB 9000 CD (1992) 2.3LL4 B234L
SAAB 9000 CD (1991) 2.3LL4 B234L
SAAB 9000 CDE (1994) 2.3LL4 B234L
SAAB 9000 CDE (1993) 2.3LL4 B234L
SAAB 9000 CS (1994) 2.3LL4 B234L
SAAB 9000 CS (1993) 2.3LL4 B234L
SAAB 9000 CSE (1994) 2.3LL4 B234L
SAAB 9000 CSE (1993) 2.3LL4 B234L
SAAB 9000 CSE TURBO (1998) 2.3LL4 B234L
SAAB 9000 CSE TURBO (1996) 2.3LL4 B234L
SAAB 9000 CSE TURBO (1995) 2.3LL4 B234L
SAAB 9000 GRIFFIN EDTION (1992) 2.3LL4 B234L
SAAB 9000 SPG (1991) 2.3LL4
TOYOTA SUPRA (1995) 3.0LL6 2JZGTE
TOYOTA SUPRA (1994) 3.0LL6 2JZGTE
TOYOTA SUPRA (1993) 3.0LL6 2JZGTE
TOYOTA SUPRA TWIN TURBO (1998) 3.0LL6 2JZGTE
TOYOTA SUPRA TWIN TURBO (1997) 3.0LL6 2JZGTE
TOYOTA SUPRA TWIN TURBO (1996) 3.0LL6 2JZGTE