American Securities Partners VI Form 4 Metaldyne Performance / Michael G. Fisch ownership change

Exhibit 99.1

Joint Filer Information

Name of Joint Filer:	American Securities Partners VI, L.P.
Address of Joint Filer:	c/o American Securities LLC
	299 Park Ave, 34th Floor
	New York, NY 10171
Relationship of Joint Filer to Issuer:	10% Owner
Issuer Name and Ticker or Trading Symbol:	Metaldyne Performance Group Inc. [MPG]
Date of Event Requiring Statement:
(Month/Day/Year):	9/1/2015
Designated Filer:	ASP MD Investco LP
Name of Joint Filer:	American Securities Partners VI(B), L.P.
Address of Joint Filer:	c/o American Securities LLC
	299 Park Ave, 34th Floor
	New York, NY 10171
Relationship of Joint Filer to Issuer:	10% Owner
Issuer Name and Ticker or Trading Symbol:	Metaldyne Performance Group Inc. [MPG]
Date of Event Requiring Statement:
(Month/Day/Year):	9/1/2015
Designated Filer:	ASP MD Investco LP
Name of Joint Filer:	American Securities Partners VI(C), L.P.
Address of Joint Filer:	c/o American Securities LLC
	299 Park Ave, 34th Floor
	New York, NY 10171
Relationship of Joint Filer to Issuer:	10% Owner
Issuer Name and Ticker or Trading Symbol:	Metaldyne Performance Group Inc. [MPG]
Date of Event Requiring Statement:
(Month/Day/Year):	9/1/2015
Designated Filer:	ASP MD Investco LP

Name of Joint Filer:	American Securities Partners VI(D), L.P.
Address of Joint Filer:	c/o American Securities LLC
	299 Park Ave, 34th Floor
	New York, NY 10171
Relationship of Joint Filer to Issuer:	10% Owner
Issuer Name and Ticker or Trading Symbol:	Metaldyne Performance Group Inc. [MPG]
Date of Event Requiring Statement:
(Month/Day/Year):	9/1/2015
Designated Filer:	ASP MD Investco LP
Name of Joint Filer:	American Securities Associates VI, LLC
Address of Joint Filer:	c/o American Securities LLC
	299 Park Ave, 34th Floor
	New York, NY 10171
Relationship of Joint Filer to Issuer:	10% Owner
Issuer Name and Ticker or Trading Symbol:	Metaldyne Performance Group Inc. [MPG]
Date of Event Requiring Statement:
(Month/Day/Year):	9/1/2015
Designated Filer:	ASP MD Investco LP

Name of Joint Filer:	American Securities LLC
Address of Joint Filer:	c/o American Securities LLC 299 Park Ave, 34th Floor
	New York, NY 10171
Relationship of Joint Filer to Issuer:	10% Owner
Issuer Name and Ticker or Trading Symbol:	Metaldyne Performance Group Inc. [MPG]
Date of Event Requiring Statement:
(Month/Day/Year):	9/1/2015
Designated Filer:	ASP MD Investco LP

Name of Joint Filer:	Kevin Penn
Address of Joint Filer:	c/o Metaldyne Performance Group Inc.
	47659 Halyard Drive
	Plymouth, MI 48170
Relationship of Joint Filer to Issuer:	Director
Issuer Name and Ticker or Trading Symbol:	Metaldyne Performance Group Inc. [MPG]
Date of Event Requiring Statement:
(Month/Day/Year):	9/1/2015
Designated Filer:	ASP MD Investco LP
Name of Joint Filer:	Loren Easton
Address of Joint Filer:	c/o Metaldyne Performance Group Inc.
	47659 Halyard Drive
	Plymouth, MI 48170
Relationship of Joint Filer to Issuer:	Director
Issuer Name and Ticker or Trading Symbol:	Metaldyne Performance Group Inc. [MPG]
Date of Event Requiring Statement:
(Month/Day/Year):	9/1/2015
Designated Filer:	ASP MD Investco LP
Name of Joint Filer:	Michael G. Fisch
Address of Joint Filer:	c/o Metaldyne Performance Group Inc.
	47659 Halyard Drive
	Plymouth, MI 48170
Relationship of Joint Filer to Issuer:	Director
Issuer Name and Ticker or Trading Symbol:	Metaldyne Performance Group Inc. [MPG]
Date of Event Requiring Statement:
(Month/Day/Year):	9/1/2015